Chain-extending phenolic end-capped polyimides

ABSTRACT

Aromatic polyimides with phenolic end groups are chain-extended (molecular weight increased) by reacting them with formaldehyde, compounds capable of generating formaldehyde under the reaction conditions or hexamethylene tetramine in the presence of a catalytic amount of lime. These polyimides can be shaped and formed prior to the chain-extending.

RELATIONSHIP TO OTHER APPLICATIONS

This application is a divisional of copending application Ser. No.363,801, filed May 25, 1973 and now U.S. Pat. No. 3,897,395.

BACKGROUND OF THE INVENTION

1. Field of Invention:

This invention relates to processes for preparing polymeric materialsand polymeric materials so prepared and more particularly to processesfor converting low molecular weight polyimides, with minimum eliminationof by-products, to high molecular weight, thermally-stable polymers.

2. Prior Art:

The synthesis in recent years of a number of thermallystable polymers(e.g. polyimides) has supplied materials whose properties allow them tomeet some critical end-use requirements. Their application to other usesis limited by a number of their specific properties, among which isintractability. This necessitates their use in dilute solutions in suchexotic solvents as sulfuric acid, for example, to be spun into fibers.This excludes their use in laminations and in moldings. In addition,once isolated from the solvent, high temperatures are required toconvert them to the fully condensed or cured final state. This curing isaccompanied by the elimination of volatile by-products.

In contrast, polymers containing oxirane structures, such asepoxy-phenolics, can be cured at reasonably low temperatures with aminimum of by-products. However, the thermal stabilities of the oxiranepolymers fall below those, for example, of the stablepolybenzimidazoles. Thus, it is desirable to prepare oligomers whichwill propagate to higher molecular weights with minimum volatileelimination at relatively low temperatures and which will possessthermal stabilities reasonably higher than epoxy phenolics, preferablyapproaching the stabilities demonstrated by the polyimides and similarpolyheterocyclics.

SUMMARY OF THE INVENTION

According to the present invention there is provided a polymericchain-extending process comprising: reacting a phenolic polyimide havingthe formula: ##STR1## wherein Ar' is a tetravalent aromatic organicradical, the four carbonyl groups being attached directly to separatecarbon atoms and each pair of carbonyl groups being attached to adjacentcarbon atoms in the Ar' radical,

Ar is a divalent aromatic organic radical,

R is an aromatic hydrocarbon radical of 6 to 12 carbon atoms, and

n is a positive integer of at least one

with a chain-extending material selected from the group consisting offormaldehyde, a compound capable of generating formaldehyde under thereaction conditions and hexamethylene tetramine in the presence of acatalytic amount of lime.

There is also provided a cross-linked polymer prepared by theabove-described process.

DETAILED DESCRIPTION OF THE INVENTION

The polyimides used in the process of the present invention are preparedby reacting an aromatic dianhydride, an aromatic diamine and,optionally, an organic monoamine to form oligomeric or higher molecularweight polyimides. The aromatic dianhydride has the general formula:##STR2## wherein Ar' is a tetravalent aromatic organic radical,preferably containing at least one ring of six carbon atoms, said ringcharacterized by benzenoid unsaturation, the four carbonyl groups beingattached directly to separate carbon atoms and each pair of carbonylgroups being attached to adjacent carbon atoms in the Ar' radical. Anyof the aromatic tetracarboxylic acid dianhydrides known in the prior artcan be used. Among the useful dianhydrides are 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, pyromelliticdianhydride, 2,3,6,7-naphthalene tetracarboxylic acid dianhydride,3,3',4,4'-diphenyl tetracarboxylic acid dianhydride,1,2,5,6,-naphthalene tetracarboxylic acid dianhydride,2,2',3,3'-diphenyl tetracarboxylic acid dianhydride,2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, bis(3,4-dicarboxyphenyl)etherdianhydride, naphthalene-1,2,4,5-tetracarboxylic acid dianhydride,naphthalene-1,4,5,8-tetracarboxylic acid dianhydride,decahydronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride,4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylicacid dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic aciddianhydride, 2,7-dichloronapthalene-1,4,5,8-tetracarboxylic aciddianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic aciddianhydride, phenanthrene-1,8,9,10-tetracarboxylic acid dianhydride,cyclopentane-1,2,3,4-tetracarboxylic acid dianhydride,pyrrolidine-2,3,4,5-tetracarboxylic acid dianhydride,pyrazine-2,3,5,6-tetracarboxylic acid dianhydride,2,2-bis(2,3-dicarboxyphenyl)propane dianhydride,1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride,1,1-bis-(3,4-dicarboxyphenyl)ethane dianhydride,bis(2,3-dicarboxyphenyl)methane dianhydride,bis(3,4-dicarboxyphenyl)methane dianhydride,bis(3,4-dicarboxyphenyl)sulfone dianhydride, andbenzene-1,2,3,4-tetracarboxylic acid dianhydride. The first threementioned dianhydrides are preferred.

Aromatic diamines useful in preparing the starting polyimides and in theprocess have the general formula:

    NH.sub.2 -- Ar-- NH.sub.2

wherein Ar is a divalent aromatic organic radical. Preferred aromaticdiamines are those wherein Ar is a divalent benzenoid radical selectedfrom the group consisting of ##STR3## and multiples thereof connected toeach other by R^(IV), e.g., ##STR4## wherein R^(IV) is an alkylene chainof 1-3 carbon atoms, --CH=CH--, ##STR5## wherein R^(V) and R^(VI) areeach selected from the group consisting of alkyl and aryl containing oneto six carbon atoms, e.g., methyl, ethyl, hexyl, n-butyl, i-butyl andphenyl.

Examples of aromatic diamines which are suitable for use in the presentinvention are 4,4'-diaminodiphenyl propane, 4,4'-diamino-diphenylmethane, benzidine, 3,3'-dichlorobenzidine, 4,4'-diamino-diphenylsulfide, 3,3'-diamino-diphenyl sulfone, 4,4'-diamino-diphenyl sulfone,4,4'-diamino-diphenyl ether, 1,5-diamino naphthalene,4,4'-diamino-diphenyl diethylsilane, 4,4'-diamino-diphenyldiphenylsilane, 4,4'-diamino-diphenyl ethyl phosphine oxide,4,4'-diaminodiphenyl phenyl phosphine oxide, 4,4'-diamino-diphenylN-methyl amine, 4,4'-diamino-diphenyl N-phenyl amine and mixturesthereof. 3,3'-dimethyl-4,4'-diaminodiphenylmethane,3,3'-diethyl-4,4'-diaminodiphenylmethane,3,3'-dimethoxy-4,4'-diaminodiphenylmethane,3,3'-diethoxy-4,4'-diaminodiphenylmethane,3,3'-dichloro-4,4',4,4'-diaminodiphenylmethane,3,3'-dibromo-4,4'-diaminodiphenylmethane,3,3'-dicarboxy-4,4'-diaminophenylmethane,3,3'-dihydroxy-4,4'-diaminophenylmethane,3,3'-disulpho-4,4'-diaminodiphenylmethane,3,3'-dimethyl-4,4'-diaminodiphenylether,3,3'-diethyl-4,4'-diaminodiphenylether,3,3'-dimethoxy-4,4'-diaminodiphenylether,3,3'-diethoxy-4,4'-diaminodiphenylether,3,3'-dichloro-4,4'-diaminodiphenylether, 3,3'-dibromo-4,4'-diaminodiphenylether, 3,3'-dicarboxy-4,4'-diaminodiphenylether,3,3'-dihydroxy-4,4'-diaminodiphenylether,3,3'-disulfo-4,4'-diaminodiphenylether,3,3'-dimethyl-4,4'-diaminodiphenylsulfide,3,3'-diethyl-4,4'-diaminodiphenylsulfide,3,3'-dimethoxy-4,4'-diaminodiphenylsulfide,3,3'-diethoxy-4,4'-diaminodiphenylsulfide,3,3'-dichloro-4,4'-diaminodiphenylsulfide,3,3'-dibromo-4,4'-diaminodiphenylsulfide,3,3'-dicarboxyl-4,4'-diaminodiphenylsulfide,3,3'-dihydroxy-4,4'-diaminodiphenylsulfide,3,3'-disulfo-4,4'-diaminodiphenylsulfide,3,3'-dimethyl-4,4'-diaminodiphenylsulfone,3,3'-diethoxy-4,4'-diaminodiphenylsulfone,3,3'-dichloro-4,4'-diaminodiphenylsulfone,3,3'-dicarboxy-4,4'-diaminodiphenylsulfone,3,3'-dihydroxy-4,4'-diaminodiphenylsulfone,3,3'-disulfo-4,4'-diaminodiphenylsulfone,3,3'-diethyl-4,4'-diaminodiphenylpropane,3,3'-dimethoxy-4,4'-diaminodiphenylpropane,3,3'-dibromo-4,4'-diaminodiphenylpropane, 3,3'-dichloro-4,4'-diaminodiphenylpropane,3,3'-dicarboxy-4,4'-diaminodiphenylpropane,3,3'-dihydroxy-4,4'-diaminodiphenylpropane,3,3'-disulfo-4,4'-diaminodiphenylpropane,3,3'-dimethyl-4,4'-diaminobenzophenone,3,3'-dimethoxy-4,4'-diaminobenzophenone,3,3'-dichloro-4,4'-diaminobenzophenone,3,3'-dibromo-4,4'-diaminobenzophenone,3,3'-dicarboxy-4,4'-diaminobenzophenone,3,3'-dihydroxy-4,4'-diaminobenzophenone,3,3'-disulphodiaminobenzophenone, 3,3'-diaminodiphenylmethane,3,3'-diaminodiphenylether, 3,3'-diaminodiphenylsulfide,3,3'-diaminodiphenylsulfone, 3,3'-diaminodiphenylpropane,3,3'-diaminobenzophenone, 2,4-diaminotoluene, 2,6-diaminotoluene,1-isopropyl-2,4-phenylenediamine, 2,4-diaminoanisole,2,4-diaminomonochlorobenzene, 2,4-diaminofluorobenzene,2,4-diaminobenzoic acid, 2,4-diaminophenol, and2,4-diaminobenzenesulfonic acid, and phenylene diamines. Preferreddiamines are 4,4'-oxydianiline, 4,4'-sulfonyldianiline, 4,4'-methylenedianiline, 4,4'-diaminobenzophenone, 4,4'-diaminostilbene and thephenylene diamines.

The polyimide starting materials used in the process of the presentinvention are prepared according to the azeotroping process described inmy copending application Ser. No. 363,800 filed May 25, 1973, thedisclosure of which is hereby incorporated by reference. Briefly, theprocess involves reacting the dianhydride with the diamine in a phenolsolvent of the formula ##STR6## where each R' is hydrogen or a methylradical in the presence of certain organic azeotroping agents,particularly cyclic hydrocarbons of 6 to 8 carbon atoms and mostpreferably benzene or toluene until most of the water of reaction iseliminated. A monoamine can also be used under certain conditions. Thereaction temperature is less than 140° C. and also should be below theboiling point of the phenol used but higher than the boiling point ofthe azeotroping agent. The vapor phase temperature lies between that ofthe water azeotrope and no higher than 95° C. As the water of reactionand azeotroping agent are removed from the reaction mixture, quantitiesof the azeotroping agent are returned to the reaction mixture so as tomaintain the temperature and reaction mixture volume substantiallyconstant. It is preferred that the process be continuous with continuousremoval of water and continuous return of azeotroping agent. This isconveniently done by the use of a conventional Dean-Stark trap andcondenser wherein after the azeotrope condenses, the water preferablysinks to the bottom of the trap for subsequent removal and theazeotroping agent overflows the trap and returns to the reactionmixture. Initially, the trap is filled with azeotroping agent.

The polyimide starting material prepared by the above-described processwill have the formula: ##STR7## wherein Ar and Ar' are as definedpreviously, ##STR8## n is 0 when X and X' are (1) or is a positiveinteger of at least one, preferably at least 4 and usually in the rangeof 4 to 20,

A is a terminal group which is --CH= CHR°, --C.tbd.CR°, --CN, --CHO,--OH, --NH₂ or --CH=NR" wherein R" is a monovalent aromatic organicradical (phenyl, naphthyl, etc.),

R is a hydrocarbon radical of 1 to 12 carbon atoms, and

R° is H or R.

When the monoamine is not used in the azeotroping process, the polyimidestarting material used in the present process will have two anhydrideend groups when the molar ratio of dianhydride to diamine in thereaction mixture is m+ 1:m or two amine end groups when the molar ratioof dianhydride to diamine is m:m+ 1 where m is a positive integer of atleast one and as high as n in the formula. Thus, the anhydrideterminated polyimide will have the formula: ##STR9## and the amineterminated polyimide can have the formula: ##STR10## In this latterevent R is also Ar.

When the molar ratio of dianhydride to diamine in the reaction mixtureis m+ 1:m, two moles of a monoamine ARNH₂ can be added to the reactionmixture to provide the terminal groups (A), i.e., --CH=CHR°,--C.tbd.CR°, --CN, --CHO, OH and --CH=NR" wherein R" is a monovalentaromatic radical. R is from 1 to 20 (preferably 1 to 10) carbon atoms.Examples of suitable amines are H₂ NCH₂ CH=CH₂, H₂ N(CH₂)₆ CH=CH₂, H₂NC₆ H₄ CH=CH₂, H₂ NCH₂ C₆ H₄ CH=CH₂, H₂ NC₆ H₄ CH₂ CH=CH₂, H₂ N(CH₂)₃ C₆H₄ CH=CH₂, H₂ NC₆ H₄ C.tbd.CH, H₂ NCH₂ C.tbd.CH, H₂ NCH₂ CN, H₂ NCH₂CH=CHCN, H₂ NCH₂ C.tbd.CCN, H₂ NC₆ H₄ CN, H₂ NC₆ H₄ OH, H₂ NC₆ H₃(CH₃)CN, H₂ NC₆ H₄ CH₂ CN, H₂ NC₆ H₄ CH₂ OH, H₂ NCH₂ C₆ H₄ CN, H₂ NCH₂C₆ H₄ OH, H₂ NC₆ H₄ CH=CHCN, H₂ NC₁₀ H₇ CN, H₂ NC₁₀ H₇ OH, H₂ NCH₂ C₆ H₄CH₂ CN, H₂ NCH₂ C₆ H₄ CH₂ OH, H₂ NC₆ H₄ CHO, H₂ NC₆ H₄ CH₂ CHO, H₂ NCH₂C₆ H₄ CH₂ CHO, H₂ NCH₂ C₆ H₄ CHO, H₂ NC₆ H₄ CH=CHCHO, H₂ NC₆ H₄ CH=NC₆H₅, H₂ NC₆ H₄ CH₂ CH=NC₆ H₄ CH₃. Preferred monoamines are allyl amine,styryl amine, propargyl amine, aminobenzyl cyanide and aminobenzylnitrile.

The chain-extending process used to make high molecular weightpolyimides will depend on the particular terminal groups present. Forexample, when the terminal groups are --CH=CHR°, --C.tbd.CR°, --CN or--CH=NR", chain extension occurs by the self-coupling of the startingpolyimide by heating, usually at a temperature in the range of about150°-450° C.

In particular, when the terminal groups are --CH=CH₂ such as when eitherallyl amine or styryl amine is used as the monoamine, chain extensionoccurs as in vinyl polymerization by thermal or free radical initiation.In this situation, any of the free radical polymerization catalysts canbe used, e.g., the peroxides such as benzoyl peroxide. A bis-maleimidecan also be copolymerized with the --CH=CH₂ terminated polyimides.Bis-maleimides are known in the art and have the formula: ##STR11##wherein Ar and Ar' are as defined previously, and n is 0 or a positiveinteger of 1 to 20. These bis-maleimides can also be prepared by theazeotroping process of my aforesaid copending application Ser. No.363,800 filed May 25, 1973. Other monovinyl or multivinyl monomers suchas the acrylics, allyl methacrylate, ethylene dimethacrylate, styrene,maleic esters and the like can also be copolymerized.

When the terminal groups are --C.tbd.CH, the polyimide can bechain-extended by catalytic polymerization in the presence of oxygenusing a cuprous salt, e.g., cuprous chloride, cuprous sulfate, cuprousacetate, etc. Generally, about 0.1 to 5% by weight of the catalyst issufficient.

Terminal groups which are --CN or --CH=NR" are polymerized using acatalytic amount of a Lewis acid salt, i.e., about 0.15 to 5 weightpercent of AlCl₃, SbCl₃, SbCl₅ or any others well-known as alkylation,isomerization or polymerization catalysts. For reasons of economy andhandling, zinc chloride, zinc sulfate and the copper salts are preferredas the coupling catalysts.

Chain extension can also occur by coupling the starting polyimide with acomplementary organic compound. The particular organic compound usedwill depend on the particular terminal groups. For example, when theterminal groups are --CH=CHR°, --C.tbd.CR°, --CN, --CHO, or --CH=NR",one mole of the polyimide can be reacted with at least 3/4 mole(preferably 1-2 moles) of an aromatic bis-dipole of the formula Q-Ar-Qwherein Ar is a divalent aromatic radical (phenyl, naphthyl, etc.) and Qis ##STR12## where R"' is an aliphatic or aromatic organic radical of 1to 12 carbon atoms, preferably an aromatic radical (e.g., --C₆ H₅, --C₆H₄ (CH₃), etc.).

The chemistry of the monofunctional dipole compounds corresponding tothe difunctional dipoles used in the present process is well known inthe art. Syntheses of the monofunctional dipole compounds areexemplified by Rolf Huisgen, Angew. Chem. Vol 75 (No. 13), pages 604-637and 742-754, 1963, and in the Proceedings of the Chemical Society ofLondon, October 1961, pages 351-369. Many of the difunctional dipolesused in the present invention are synthesized by the same techniquesdescribed in these references as well as in U.S. Pat. Nos. 3,390,204,3,390,132 and 3,213,068. Preferred dipole compounds are1,4-benzenedinitrile oxide, 1,4-benzenedi(phenylnitrilimine) and1,4-benzenedi(phenylnitrile ylide).

To increase the rate of reaction between the polyimide and bis-dipole,the concentration of the bis-dipole can be increased up to 2 moles. Thereaction can take place at ambient temperatures or slightly higher, butonce initiated, the temperature can go as high as the boiling point ofany solvent used, usually a phenol or the accepted aprotic polymersolvents disclosed in my copending application Ser. No. 363,799, filedMay 25, 1973.

The bis-maleimides described above are known to react with dipoles, butthe thermal stability of the resulting product is low. I have discoveredthat if polyimide character, i.e., ##STR13## is interjected between themaleimides, then the cycloaddition extension products have improvedthermal stability.

The reaction between the bis-dipolar compound and the reactive end groupis a 1,3-dipolar cycloaddition reaction which does not eliminateby-products during the course of propagation. For example, if styryl isthe reactive end group and 1,4-benzenedinitrile oxide is used as thedipolar compound, the mode of propagation can be shown as follows:##STR14##

When the terminal groups are --OH, the complementary organic compound isformaldehyde, a compound capable of generating formaldehyde under thereaction conditions such as paraformaldehyde or hexamethylene tetramine.The reaction is preferably carried out in the presence of lime as acatalyst with about 1 to 5 weight percent lime, based on the weight ofpolyimide, usually being sufficient. The amount of formaldehyde used isusually in the range of about 10 to 15% by weight, based on the weightof polyimide, but can range from about 5 to 25% by weight and evenhigher; however, there is usually no economic incentive for using higherconcentrations.

For the purpose of this invention, the term formaldehyde and compoundscapable of generating means formaldehyde itself (CH₂ O), polymers offormaldehyde (CH₂ O)_(x) such as paraformaldehyde, formaldehyde in anaqueous solution in which formaldehyde exists as a methylol compound(HOCH₂ OH) having a reactivity equivalent to formaldehyde. These are allcapable of resinifying phenols by the well-known Bakelite reaction. Theterm also means addition compounds of formaldehyde with amidogens having2-6 methylol functions such as methylol ureas, trimethylol melamine,hexamethylol melamine and the methylol guanidines, or the methylolphenols such as 1,3,5-trimethylol phenol or condensed derivativesthereof, or the phenol alcohols such as 1,5-dimethylol para cresol andphenol phenol - all of which can resinify, i.e. chain-extend phenolseither by direct reaction or by engendering formaldehyde or both. Theterm also includes substituted formaldehydes (ZCHO), where Z is ahydrocarbon radical of 1-12 carbon atoms, such as acetaldehyde, acroleinand the like, the substituted formaldehydes where another aldehyde groupis attached directly or indirectly to the --CHO moiety as in glyoxal(OHCCHO), succinyl dialdehyde (OCHCH₂ CH₂ CHO), glutaraldehyde(OHC(CH₂)₃ CHO) or terephthaldehyde (OHCC₆ H₄ CHO) and the well-knownresinifying aldehyde furfuraldehyde.

The dianhydride terminated polyimides are chain-extended by reactingthem with an aromatic diisocyanate of the formula Ar(NCO)₂ wherein Ar isa divalent aromatic organic radical preferably such as tolylene (CH₃ C₆H₃ <), xylylene (--CH₂ C₆ H₄ CH₂ --), benzylene (--C₆ H₄ CH₂ --),phenylene (C₆ H₄ <), naphthylene (C₁₀ H₆ <), diphenylene (C₁₂ H₈ <) andgenerally any of the other Ar radicals listed with the aromatic diaminesabove, to yield thermally stable foams under appropriate processingconditions.

The anhydride terminated polyimides can also be chain-extended byreacting them with any of the aromatic diamines previously described,preferably sulfonyl dianiline and oxydianiline, or by reacting them witha diamine terminated imide oligomer which can be prepared by myaforesaid application Ser. No. 363,800, filed May 25, 1973. Thisoligomer has the formula: ##STR15## wherein Ar and Ar' have been definedpreviously and, n is a positive integer of at least 1, preferably 4 to20.

The reaction of the diamine and diamine terminated oligomer with thedianhydride preferably can be carried out at a temperature above themelting point of the materials involved or preferably in the phenolsolvent defined previously, preferably m-cresol or a mixture of m-cresolwith its other isomers, as well as in any of the accepted aproticpolymer solvents mentioned previously.

The diamine terminated polyimides are chain-extended by reacting themwith an anhydride of the formula ##STR16## wherein p is 2 or 3 and Ar'is any of the radicals listed with the aromatic dianhydrides above whenp is 2. When p is 3 Ar' is a hexavalent aromatic organic radical, thesix carbonyl groups being attached directly to separate carbon atoms andeach pair of carbonyl groups being attached to adjacent carbon atoms inthe Ar' is radical. Preferred anhydrides are mellitic dianhydride,mellitic trianhydride and 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride. This reaction can be carried out at a temperature above themelting point of the diamine terminated polyimide or preferably in anyof the solvents defined previously (preferably m-cresol or a mixture ofm-cresol and its isomers). Instead of the di- or trianhydride, itscorresponding tetra or hexa carboxylic acid can be used.

The polyimides of the present invention have a number of uses. Theseinclude use of the solutions before curing as wire and insulatingvarnishes and to impregnate fabric substrates used in making flexibleand rigid electronic circuit boards and in making structural laminates.The solutions can be used to make fibers and films and as adhesives,particularly for film substrates, useful in aerospace and electronicsapplications. The powders can be used as molding powders and to makefibers, films and foams.

The invention can be further understood by the following examples inwhich parts and percentages are by weight unless otherwise indicated.

EXAMPLE 1

(a) Preparation of Amine-Terminated Oligomeric Polyimide (BTAT-3).Reactionof BTCA and ODA (7:8).

An apparatus consisting of a 100 ml. three-neck, round-bottom flaskequipped with a magnetic stirrer, Dean-Stark trap and condenser, adropping funnel, heating mantle, etc. is used in this and numerousfollowing syntheses. For purposes of brevity, it will be called "them-cresol:benzene azeotropic apparatus."

In the m-cresol:benzene azeotropic apparatus was placed4,4'-oxydianiline (ODA) (3.204 g., 0.016 mole) in 20 ml. of m-cresol and10 ml. of benzene. After warming to 60° C., a solution of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTCA) (4.512 g.,0.014 mole) in 30 ml. m-cresol was added. A copious yellow precipitateformed immediately. The reaction mixture was heated to reflux and thesolid material dissolved, forming a orange solution. After 2 hours ofreflux, 0.30 ml. of water has been collected and a precipitate hadformed in the reaction flask. After cooling, the reaction mixture wasconcentrated on a rotary flash evaporator and then vacuum-dried at 170°C. to give 7.0960 g. (˜100%) of a yellow solid which wasslightly solublein m-cresol, and insoluble in sulfolane and DMAC. On a Fisher-Johnsmelting point apparatus it softened slightly at about 210° C., partiallymelted by 235° C., and rehardened to a granular solid at 240° C.

Analysis: Calc'd. for C₂₁₅ H₁₁₀ N₁₆ O₄₃ : C, 72.18; H, 3.10; N, 5.48.Found: C, 70.26; H, 3.26; N, 6.11.

(b) Preparation of Oligomeric Anhydride (BTOD-1). Reaction of BTCA andODA (2:1).

Into a 100 ml. three-neck, round-bottom flask equipped with a magneticstirrer, thermometer, condenser, gas inlet tube, dropping funnel, etc.there was place, under nitrogen atmosphere, a solution of BTCA (6.444g., 0.02 mole) in 25 ml. of DMAC. Then, a solution of ODA (2.00 g., 0.01mole)in 15 ml. of DMAC was added over a period of 15 minutes. Thereaction, which was exothermic, was maintained at 40° C. during theaddition,following which it was heated at 85°-90° C. for 15 minutes. Tothis clear amber-colored solution, acetic anhydride (3.06 g., 0.03 mole)was added and the mixture was heated to 125° C. Within 15 minutes, ayellow precipitate formed. After heating, the reaction mixture for 1hour, the solvents were removed in a rotary flash evaporator. Theresidual light-yellow solid was washed with anhydrous ether and dried inavacuum oven at 140° C., to afford a quantitative yield. It softenedslightly on a Fisher-Johns melting point apparatus at 120° C. and didnot melt when heated to 300° C. The product was soluble in m-cresol andN-methyl-2-pyrrolidone and only slightly soluble in boilingbenzonitrile, acetophenone or DMAC.

Its infrared spectrum shows the peaks for --C=O of the anhydride groupat 4.50 and 5.63μ, and for the imide C=O, at 5.82μ.

Analysis: Calc'd. for C₄₆ H₂₀ N₂ O₁₃ : C, 68.32; H, 2.49; N, 3.47.Found: C, 68.27; H, 2.82; N, 3.79.

(c) Melt reaction of BTAT-3and BTOD-1.

An intimate mixture of equimolar amounts of BTOD-1 and BTAT-3 was placedbetween glass plates and placed on a block preheated to 250° C.Thesample melted and rehardened within 3 minutes. Then, as thetemperature wasraised at 5° C./minute, the sample resoftened at 290° C.,andrehardened at about 325° C.

EXAMPLE 2

(a) Preparation of Foamed Polyimide (BTFM-1). Reaction of BTOD-1 andTolylene-2,4-diisocyanate (TDI) (1:1).

An intimate mixture of BTOD-1 prepared in Example 1 (b) (0.081 g.,0.0001 mole) and TDI (0.017 gl, 0.0001 mole) was prepared in a Wig-L-jigapparatus. A small sample of the mixture was placed between glass platesand placed onto a block preheated to 250° C. The entire sample melted,foamed and hardened within 1 minute.

(b) Preparation of Foamed Polyimide (BTFM-2). Reaction of BTOD-1 and TDI(1:2).

An intimate mixture of BTOD-1 prepared in Example 1 (b) (0.81 g., 0.0001mole) and TDI (0.034 g., 0.0002 mole) was prepared in a Wig-L-jigapparatus. A small sample of the mixture was placed between glass platesand placed onto a block preheated to 250° C. The entire sample melted,foamed and hardened within 10 seconds. The volume increase wasnoticeably greater in this case than (a) above.

EXAMPLE 3

(a) Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-4).Reaction of BTCA, DAPB-3,3, ODA and AS in 9:(4:4):2 Mole Ratio.

In a large-scale m-cresol:benzene azeotropic apparatus was placed, undera slow nitrogen sweep, BTCA (21.7505 g. 0.0675 mole), 175 ml. ofm-cresol and 50 ml. of benzene. The mixture was warmed to approximately70° C. to dissolve the BTCA and then a solution of m-aminostyrene (AS)(1.7874g., 0.015 mole) in 25 ml. of m-cresol, containing 0.1 g. oft-butyl catechol, was added over approximately 1/2 hour. The solutionwas then refluxed for 20 minutes. Then a solution of1,3-di(3-aminophenoxy)benzene (DAPB-3,3) (8.7699 g., 0.030 mole) and ODA(6.0072 g., 0.030 mole) in 75 ml. of m-cresol was added. Reflux wasmaintained for 3 hours; 2.47 ml. of water was collected. Then 50 ml. ofbenzene was distilled off.

After cooling to ambient temperature, the clear solution was addeddropwiseto 600 ml. of well-stirred methanol. After stirring for 2 hours,the solution was filtered. The isolated solid was heated in 200 ml. ofboilingmethanol containing approximately 0.1 g. of t-butyl catechol for1 hour andfiltered. The methanol wash was repeated three times. A smallportion of the solid was removed and treated in boiling inhibitor-freemethanol. Thissmall sample was used for testing purposes, such asmelting behavior, solubility, etc. The remainder of the material wasvacuum-dried at ambienttemperature for 40 hours, to give BTAS-4 as ayellow solid, 36.9 g. (103%).A TGA in nitrogen showed a loss ofapproximately 5% volatiles before an inflection point at approximately510° C. The sample was washed once more with hot methanol andvacuum-dried at 40° C. for 16 hoursto give 35.3 g. (98%). A TGA innitrogen showed approximately 2% volatiles.

BTAS-4 was soluble in m-cresol and sulfolane, was partially soluble inhot DMAC and hot DMF, swelled slightly in dioxane, styrene, 75% DVB andchloroform, but was insoluble in methanol and benzene. When heated fromambient to higher temperatures on a Fisher-Johns melting point block,BTAS-4 softened at 185°-205° C., was partially molten at approximately220° C., was a thick 235° C., and hardened after 20 minutes at 300° C.Its TGA in nitrogen showed an inflection point at approximately 510° C.and a 58% residue at 1000° C. The DTA displayed an endotherm (softeningor melting) in the region of 190° C., which was followed immediately bya strong exotherm (polymerization) in the region of 190°-210° C.,followed by a weak endotherm which blends into a second mild exotherm atapproximately 260° C. A 0.20 g. sample of BTAS-4 was heated in an airoven at 200° C. for 5 hours to give BTAS-4-H200. The TGA of BTAS-4-H200in nitrogen and in air showed the samples to be substantially free ofm-cresol. The inflection points in nitrogen and in air are almostidentical in the 500° C. region; the difference in nitrogen and in airis found in a char residue of 60% to 0% respectively, at temperatureshigher than 600° C.

Analysis: Calc'd for C₂₈₉ H₁₄₈ N₁₈ O₅₇ : C, 72.55; H, 3.12; N, 5.27; O,19.06. Found: C, 72.54; H, 3.20; N, 5.32: O, -- .

(b) Reaction of BTAS-4 with ODA.

To a solution of BTAS-4 (0.4882 g., 0.0001 mole) in 14 ml. of m-cresolwas added a solution of ODA (0.020 g., 0.0001 mole) in 1 ml. ofm-cresol. The solutions were mixed in a small flask and placed in an airoven at 100° C. The temperature was raised slowly to 200° C. over aperiod of 6 hours to eliminate solvent and maintained at 200° C. for 24hours. The cured product was obtained as dark-brown chips. The productwas hard and tough, and required grinding in Wig-l-jig apparatus for 10minutes to produce a powder, which was vacuum-dried at 200° C. for 24hours, to give 0.5091 g. (100%). Its infrared spectrum (KBr disc) wasrecorded. Its TGA in nitrogen and in air showed, in both cases,inflection points in the region of 500° C. The product cured at 200° C.was insoluble in boiling m-cresol.

(c) Thermal Polymerization of BTAS-4 in m-Cresol.

BTAS-4 (0.4882 g., 0.0001 mole) in 5 ml. of m-cresol was heatedaccording to the schedule given directly above to afford 0.4778 g. (98%)of dark glassy chips. Its infrared spectrum was recorded. Its TGA innitrogen showed an inflection point in the 500° C. region. The productcuredat 200° C. is insoluble in boiling m-cresol.

(d) Thermal Catalyzed Polymerization of BTAS-4.

BTAS-4 (0.4882 g., 0.0001 mole) and benzoyl peroxide (0.005 g.) in 5 ml.ofm-cresol were heated according to the schedule given above. There wasobtained 0.4820 g. (99%) of a dark glassy solid. Its infrared spectrumwassimilar to that of cured BTAS-4.

EXAMPLE 4

(a) Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-9).Reaction of BTCA, DAPB-3,3, and AS in 9:8:2 Mole Ratio.

In an m-cresol:benzene azeotropic apparatus was placed, under a slownitrogen sweep, BTCA (2.175 g., 0.0675 mole), 10 ml. of m-cresol and 10ml. of benzene. The mixture was warmed to approximately 70° C. todissolve the BTCA and then a solution of AS (0.1787 g., 0.015 mole) in25 ml. of m-cresol, containing 0.1 g. of t-butyl catechol, was addedover approximately 1/2 hour. The solution was then refluxed for 20minutes. Then a solution of DAPB-3,3 (1.7540 g., 0.060 mole) in 7.5 ml.of m-cresolwas added. Reflux was maintained for 3 hours and then 10 ml.of benzene wasdistilled off.

After cooling to ambient temperature, the clear solution was addeddropwiseto 600 ml. of well-stirred methanol. After stirring for 2 hours,the solution was filtered. The isolated solid was heated in 200 ml. ofboilingmethanol containing approximately 0.1 g. of t-butyl catechol for1 hour andfiltered. The methanol wash was repeated three times. A smallportion of the solid was removed and treated in boiling inhibitor-freemethanol. Thissmall sample was used for testing purposes, such asmelting behavior, solubility, etc. The remainder of the material wasvacuum-dried at ambienttemperature for 40 hours, to give BTAS-9 as alight-yellow solid, 3.6 g. (92%).

BTAS-9 was soluble in m-cresol, DMAC, DMF, sulfolane, dioxane,chloroform and methylene chloride; it was partially soluble in hottetrahydrofuran; it swelled in divinyl benzene, cis-1,2-dichloroethyleneand methyl methacrylate and was insoluble in methylethyl ketone andtrans-1,2-dichloroethylene. BTAS-9 melts in the 170°-205° C.range,thickens above 210° C. and rehardens at 230° C.

A small sample was vacuum dried at 200° C. to yield BTAS-9-H200 andanalyzed.

Analysis: Calc'd. for C₃₁₃ H₁₆₄ N₁₈ O₆₁ : C, 72.96; H, 3.21; N, 4.89; O,18.94. Found: C, 73.04; H, 3.39; N, 4.64; O, --.

(b) Catalyzed Polymerization of BTAS-9.

In a small beaker was placed a solution of the oligomer BTAS-9 (0.250g.) in 5 ml. of DMAC. Then there was added benzoyl peroxide (0.00259)and the solution was placed in an air oven at 100° C. for 24 hours. Thenthe temperature was raised to 200° C. over 8 hours and then maintainedat 200° C. for 60 hours. There was obtained a dark film (BTAS-9-cured).The polymer was insoluble in hot m-cresol.

EXAMPLE 5

(a) Preparation of Styrene-Terminated Oligomeric Polyimide (NTAS-1).Reaction of 1,4,5,8-Naphthalenetetracarboxylic Acid Dianhydride (NTCA),DAPB-3,3 and AS (9:8:2).

Using the m-cresol:benzene azeotropic apparatus procedure describedpreviously, there was allowed to react1,4,5,8-naphthalene-tetracarboxylicacid dianhydride (NTCA) (2.8369 g.,0.01125 mole), DAPB-3,3 (2.9233 g., 0.01 mole) and AS (0.2979 g., 0.0025mole). There was obtained NTAS-1, 4.4712 g. (79.1%) as a tan powderwhich partially melted, with darkening at 220°-260° C., rehardened at265° C., and then did not change up to 300° C. When a sample was placedon a Fisher-Johnsapparatus at approximately 220° C., it becamecompletely molten by 260° C. and rehardened at about 265° C.

NTAS-1 was soluble in DMAC, m-cresol, sulfolane and concentratedsulfuric acid, and swelled in hot dioxane. Its infrared spectrum wasconsistent with that expected for the compound.

Analysis: Calc'd. for C₂₈₆ H₁₄₆ N₁₈ O₅₂ : C, 73.61; H, 3.15; N, 5.40; O,17.83. Found: C, 73.74; H, 3.50; N, 5.83; O, --

(b) Catalyzed Polymerization of NTAS-1.

The oligomer, NTAS-1 (0.250 g.) in 5 ml. of DMAC was cured with benzoylperoxide (0.0025 g.) according to the schedule given in Example 4(b).There was obtained a dark granular solid (NTAS-1-cured). The polymer wasinsoluble in hot m-cresol.

EXAMPLE 6

(a) Preparation of Nitrile-Terminated Oligomeric Polyimide BTAN-6.Reactionof BTCA, MDA-4,4 and AN (9:8:2).

In a m-cresol:benzene azeotropic apparatus was placed (2.1751 g., 0.0135mole) and 4-aminobenzonitrile (AN) (0.1772 g., 0.0030 mole) in 25 ml. ofm-cresol and 10 ml. of benzene. The mixture was brought to reflux andmaintained at reflux for 30 minutes. Then a solution of 4,4'-methylenedianiline (MDA-4,4) (1.1896 g., 0.0120 mole) in 15 ml. of m-cresol wasadded and the mixture was refluxed for 30 minutes. At the end of thereflux period the theoretical amount of water had been collected and thereaction mixture was a clear yellow solution. Then the reaction mixturewas added dropwise to approximately 100 ml. of methanol. Theprecipitated oligomer was digested three times in 100 ml. of hotmethanol, filtered andvacuum-dried at 70° C. for 24 hours. A pale yellowpowder, BTAN-6, 2.1102 g. (94%) was obtained. On a Fisher-Johns meltingpoint apparatus BTAN-6 melted over the range 230°-290° C. The drop meltwas 270° C. It was soluble in m-cresol and sulfolane and becameswollenin DMAC and dioxane.

(b) Preparation of Nitrile-Terminated Oligomeric Polyimide BTAN-7.Reactionof BTCA, MDA-4,4, SDA-3,3 and AN (9:4+4:2).

According to the procedure reported in (a) above for the preparation ofBTAN-6, there was allowed to react BTCA (2.9001 g., 0.009 mole), MDA-4,4(0.7930 g., 0.004 mole), 3,3'-sulfonyldianiline (SDA-3,3) (0.9932 g.,0.004 mole) and AN (0.2363 g., 0.002 mole). The reaction mixture was aclear yellow solution at the end of a 3-hour reflux period. Afterprecipitation and vacuum-drying at 70° C. for 24 hours there wasobtained BTAN-7 as a pale yellow powder, 4.1594 g. (90.4%). On aFisher-Johns apparatus BTAN-7 melted over the range 255°-285° C. Thedrop melt was 260° C. BTAN-7 was soluble in m-cresol, sulfolane andDMAC.

(c) Preparation of Nitrile-Terminated Oligomeric Polyimide BTAN-8.Reactionof BTCA, MDA-4,4, SDA-3,3 and AN (9:6+2:2).

The procedure reported in (a) above for the preparation of BTAN-6 wasrepeated except that BTCA (2.9001 g., 0.009 mole), MDA-4,4 (1.996 g.,0.006 mole), SDA-3,3 (0.4966 g., 0.002 mole), and AN (0.2363 g., 0.002mole) were allowed to react. The reaction mixture remained clearthroughout a 3-hour reflux period. After the usual isolation procedurethere was obtained BTAN-8 as a pale yellow powder, 4.2198 g. (94%) whichwas soluble in m-cresol and sulfolane. It became swollen in DMAC. On aFisher-Johns apparatus BTAN-8 melted over the range 240°-280° C. Thedrop melt was 265° C.

(d) Preparation of Nitrile-Terminated Oligomeric Polyimide BTAN-9.Reactionof BTCA, MDA-4,4, SDA-3,3 and AN (9:7+1:2).

The procedure reported in (a) above for the preparation of BTAN-6 wasrepeated using BTCA (2.9001 g., 0.009 mole), MDA-4,4 (1.3878 g., 0.007mole), SDA-3,3 (0.2483 g., 0.001 mole) and AN (0.2363 g., 0.002 mole).Thereaction mixture remained clear during a 3-hour reflux period. Therewas obtained BTAN-9 as a pale yellow powder, 4.1670 (94%) which wassoluble inm-cresol, partially soluble in hot sulfolane and insoluble inDMAC. On a Fisher-Johns apparatus BTAN-9 melted over the range 230°-290°C. The drop melt was 280° C.

(e) Preparation of Nitrile-Terminated Oligomeric Polyimide BTAN-10.Reaction of BTCA, MDA-4,4, SDA-3,3 and AN (9:7.5+0.5:2).

The procedure reported in (a) above for the preparation of BTAN-6 wasrepeated using BTCA (2.9001 g., 0.009 mole), MDA-4,4 (0.4870 g., 0.0075mole), SDA-3,3 (0.1242 g., 0.0005 mole) and AN (0.2363 g., 0.002 mole).Atthe end of a 3-hour reflux period the reaction mixture was slightlyhazy. There was obtained BTAN-10 as a pale yellow powder, 4.1140 g.(93%), whichwas soluble in m-cresol, partially soluble in sulfolane andinsoluble in DMAC. On a Fisher-Johns apparatus BTAN-10 melted over therange 250°-280° C. The drop melt was 270° C.

(f) Curing of Nitrile-Terminated Oligomeric Polyimides, BTAN-6 throughBTAN-10.

Intimate mixtures (˜0.25 g.) of each of the nitrile-terminatedoligomeric polyimides, BTAN-6 through BTAN-10 with Cu₂ Cl₂ (5% byweight) were prepared in a Wig-L-jig apparatus. A single mixture ofBTAN-6 with Cu₂ Cl₂ was prepared similarly. Then samples of eachof themixtures were placed into a test tube, the tube was flushed withnitrogen and capped with a nitrogen-filled balloon. The tubes were thenplaced into a metal block preheated to and electronically maintained at300° C. After 2 hours the tubes were removed and allowed to cool. Thenthe TGA in air and in nitrogen of each of the samples was performed at10° C./minute on a Du Pont 900. The pertinent data for these reactionsare given in Table I.

                                      TABLE I                                     __________________________________________________________________________    Data on Curing of Nitrile-Terminated Oligomeric Polyimides BTAN-6 through     BTAN-10.                                                                                        TGA : Percent Residue at                                                                              TGA                                      Weight   Weight                                                                            Atmos-                  Break                                                                             Inflec-                         Oligomer                                                                           (g.)                                                                              Catalyst                                                                           (g.)                                                                              phere                                                                             300° C.                                                                    400° C.                                                                    500° C.                                                                    600° C.                                                                    700° C.                                                                    ° C.                                                                       tion ° C.                __________________________________________________________________________    BTAN-6                                                                             0.250                                                                             Cu.sub.2 Cl.sub.2                                                                  0.0125                                                                            Air 100 95   0  0    0  365 --                                                N.sub.2                                                                           100 99  94      57  370 535                             BTAN-6                                                                             0.500                                                                             Cu.sub.2 Cl.sub.2                                                                  0.025                                                                             Air 100 98   8  0    0  360 --                                                N.sub.2                                                                           100 99  95      59  370 550                             BTAN-7                                                                             0.250                                                                             Cu.sub.2 Cl.sub.2                                                                  0.0125                                                                            Air 100 98   0  0    0  350 --                                                N.sub.2                                                                           100 99  94      58  360 540                             BTAN-8                                                                             0.250                                                                             Cu.sub.2 Cl.sub.2                                                                  0.0125                                                                            Air 100 98    0 0    0  370 --                                                N.sub.2                                                                           100 99  94      62  370 550                             BTAN-9                                                                             0.250                                                                             Cu.sub.2 Cl.sub.2                                                                  0.0125                                                                            Air 100 88   0  0    0  340 --                                                N.sub.2                                                                           100 99  93      60  360 545                             BTAN-10                                                                            0.250                                                                             Cu.sub.2 Cl.sub.2                                                                  0.0125                                                                            Air 100 85   0  0    0  340 --                                                N.sub.2                                                                           100 99  94      57  350 555                             __________________________________________________________________________

EXAMPLE 7

A. Preparation of Amine Terminated Oligomers:

(a) Preparation of Amine-Terminated Oligomeric Polyimide (BTAT-4).Reactionof BTCA and SDA-3,3 (4:5).

In a m-cresol:benzene azeotropic apparatus was placed BTCA (11.2781 g.,0.035 mole), SDA-3,3 (10.8760 g., 0.0438 mole), 80 ml. of m-cresol and10 ml. of benzene. The mixture was refluxed for 31/2 hours during whichtime1.3 ml. of water was collected. Then, the benzene was distilled offand thesolution was precipitated in methanol. The precipitated oligomerwas digested three times in hot methanol and then vacuum dried at 70° C.for 24 hours to give BTAT-4, 19.7498 g. (95%) as a light-yellow solidwhich was soluble in m-cresol, DMAC and sulfolane. It swelled in hotdioxane. On a Fisher-Johns apparatus, it softened slightly above 180°C., melted at 245°-280° C. and rehardened after 5 minutes at 300° C. Thelowest temperature at which a sample wouldmelt completely when droppedonto the preheated block was 270° C.

A sample was vacuum-dried at 200° C. and submitted for analysis.

Analysis: Calc'd. for C₁₂₈ H₆₈ N₁₀ O₃₀ S₅ : C, 64.42; H, 2.87; N, 5.87;O, 20.12; S, 6.72. Found: C, 63.71; H, 2.91; N, 5.75; O, --; S, --.

(b) Preparation of Amine-Terminated Oligomeric Polyimide (BTAT-5).Reactionof BTCA and SDA-3,3 (8:9).

According to the procedure used in (a) above, there was allowed to reactBTCA (11.2781 g., 0.035 mole) and SDA-3,3 (9.7834 g., 0.0394 mole) in 80ml. of m-cresol and 10 ml. of benzene. There was obtained the oligomer,BTAT-5, as a light-yellow solid, 18.3 g. (92.5%) which was soluble inm-cresol, DMAC and sulfolane. It swelled in hot dioxane. On aFisher-Johnsapparatus it began to melt at 255° C. but was not completelymelted by 300° C., at which temperature it hardened in 3 minutes. Thelowest temperature at which a sample would melt completely when droppedonto the preheated block was 280° C.

The analysis was performed on a small sample vacuum-dried at 200° C.

Analysis: Calc'd. for C₂₄₄ H₁₂₄ N₁₈ O₅₈ S₉ : C, 64.77; H, 2.76; N, 5.57;O, 20.51; S, 6.38. Found: C, 63.54; H, 2.81; N, 5.45; O, --; S, --.

(c) Preparation of Amine-Terminated Oligomeric Polyimide (BTAT-6).Reactionof BTCA and DAPB-3,3 (4:5).

According to the procedure in (a) above, BTCA (3.2223 g., 0.01 mole) andDAPB-3,3 (3.6529 g., 0.0125 mole) were allowed to react. There wasobtained BTAT-6, 6.1215 g. (94%) as a yellow powder. On a Fisher-Johnsmelting point apparatus BTAT-6 melted from 180°-200° C. and rehardenedafter 30 minutes at 300° C. The lowest temperature at which a samplecompletely melted when dropped onto a preheated block was 190° C. BTAT-6was soluble in m-cresol, DMAC, sulfolane and dioxane.

A sample was vacuum-dried at 200° C. for analysis.

Analysis: Calc'd. for C₁₅₈ H₈₈ N₁₀ O₃₀ : C, 72.81; H, 3.40; N, 5.37; O,18.42. Found: C, 72.72; H, 3.35; N, 4.77; O --

(d) Preparation of Amine-Terminated Oligomeric Polyimide (BTAT-7),Reactionof BTCA and DAPB-3,3 (8:9).

According to the procedure in (a) above, BTCA (3.2223 g., 0.01 mole) andDAPB-3,3 (3.2887 g., 0.01125 mole) were allowed to react. There wasobtained BTAT-7 as a yellow powder, 5.8708 g. (95.4%). On a Fisher-Johnsapparatus BTAT-7 began to melt from 190° C. but did not completely meltby 300° C., when it hardened in 30 minutes. The lowest temperature atwhich a sample melted when dropped onto a preheated block was 220° C.BTAT-6 was soluble in m-cresol, DMAC, sulfolane and dioxane.

A small sample was vacuum-dried at 200° C. for analysis.

Analysis: Calc'd. for C₂₉₈ H₁₆₀ N₁₈ O₅₈ : C, 72.74; H, 3.28; N, 5.12; O,18.86. Found: C, 72.45; H, 3.31; N, 5.04; O --

B. Preparation of Anydride-Terminated Oligomers:

(a) Preparation of Anhydride-Terminated Oligomeric Polyimide (BTOD-3).Reaction of BTCA and SDA-3,3 (5:4).

According to the procedure used in A(a) above, there was allowed toreact BTCA (12.0827 g., 0.0375 mole) and SDA-3,3 (7.4493 g., 0.03 mole)in 80 ml. of m-cresol and 10 ml. of benzene. There was obtained theoligomer BTOD-3, as a light-yellow solid, 16.9 g. (92%) which wassoluble in m-cresol, DMAC, DMF and sulfolane. It softened at 240° C.,melted from 245°-265° C., with the evolution of small amounts of gas,and did not harden during 30 minutes at 300° C. The lowest temperatureat which a sample melted completely when dropped onto a preheated blockwas 255° C.

A small sample was vacuum-dried at 200° C. and submitted for analysis.

Analysis: Calc'd. for C₁₃₃ H₆₂ N₇ O₃₅ S₄ : C, 65.30; H, 2.56; N, 4.01;O, 22.89; S, 5.24. Found: C, 63.90; H, 2.74; N, 4.70; O, --S, --.

(b) Preparation of Anhydride-Terminated Oligomeric Polyimide (BTOD-4).Reaction of BTCA and SDA-3,3 (9:8).

According to the procedure used in A(a) above, there was allowed toreact BTCA (14.5003 g., 0.045 mole) and SDA-3,3 (9.9324 g., 0.04 mole)in 90 ml.of m-cresol and 20 ml. of benzene. There was obtained theoligomer, BTOD-4,as a light-yellow solid, 21.4 g. (95%) which wassoluble in m-cresol, DMAC,DMF and sulfolane. It began to melt at 265° C.with the evolution ofsmall amounts of gas, but was not melted completelyby 300° C. and did not harden during 15 minutes at 300° C. The lowesttemperature at which a sample melted completely when dropped onto apreheated block was 270° C.

A small sample vacuum-dried at 200° C. was submitted for analysis.

Analysis: Calc'd. for C₂₄₉ H₁₁₈ N₁₅ O₆₃ S₈ : C, 65.24; H, 2.60; N, 4.58;O, 21.99; S, 5.60. Found: C, 63.99; H, 2.73; N, 4.95; O, --S, --.

(c) Preparation of Anhydride-Terminated Oligomeric Polyimide (BTOD-5).Reaction of BTCA and DAPB-3,3 (5:4).

According to the procedure used in A(a) above, there was allowed toreact BTCA (4.0279 g., 0.0125 mole) and DAPB-3,3 (2.9223 g., 0.01 mole)in 40 ml. of m-cresol and 10 ml. of benzene. There was obtained theoligomer BTOD-5 (5.7678 g., 80%) as a light-yellow powder which wassoluble in m-cresol, DMAC, sulfolane and dioxane. On a Fisher-Johnsmelting point apparatus BTOD-5 melted over the range of 190°-205° C.with gas evolution and did not harden during 10 minutes at 300° C. Thelowest temperature at which a sample melted completely when dropped ontoapreheated block was 200° C.

Analysis: Calc'd. for C₁₅₇ H₇₈ N₈ O₃₅ : C, 71.52; H, 2.98; N, 4.25; O,21.24. Found: C, 71.41; H, 3.21; N, 4.46; O, --.

(d) Preparation of Foamed Polymer by Reaction of a Diisocyanate and anOligomeric Anhydride Terminated Polyimide.

The procedure of Example 7B(c) was used to prepare an oligomer of BTCAand DAPB-3,3 in a 9:8 mole ratio (BTOD-20).

A mixture of oligomer (BTOD-20) (0.5495 g., 1 × 10⁴ mole) and TDI(0.0522 g., 3 × 10⁴ mole) was packed tightly into a pyrex tube. The tubewas then flushed well with nitrogen gas, and a balloon, which was filledwith nitrogen gas, was attached to the pyrex tube. The tube was theninserted into a thermostatically controlled metal block, preheated to225° C., causing the mixture to form a foamed structure within a fewminutes, which did not collapse when heating was continued for 3 hours.A sample of the foamed product was insoluble in cold m-cresol butswelled in hot m-cresol. The foamed product was then heated at 300° C.in air over 2 hours whose TGA in air showed an inflection point in the525° C. region. In nitrogen the clear residue at 1000° C. amounted to60%.

C. Preparation of Polyimide Polymer Components:

Intimate mixtures of the various reactants prepared in A. and B. aboveand BTCA, SDA-3,3 and mellitic trianhydride (MTA) were prepared forpolymerization in a Wig-L-jig apparatus. The various polymers and theircomponents are listed in Table II.

                                      TABLE II                                    __________________________________________________________________________    Components Used in the Preparation of PIB-Type Polymers                       Components                                                                         Amine or Amine-                                                                         Anhydride or Anhydride-                                             Terminated Oligomer                                                                     Terminated Oligomer                                                                       Crosslinking Agent                                 Polymer                                                                            (grams ,  moles)                                                                        (grams ,  moles)                                                                          (grams , moles)                                    __________________________________________________________________________         BTAT-4    BTOD-3                                                         PIB-1                                                                              0.2393 g., 0.0001 m                                                                     0.2446 g., 0.0001 m                                                                       none                                                    BTAT-4    BTOD-3      BTAT-4                                             PIB-1A                                                                             0.2393 g., 0.0001 m                                                                     0.2446 g., 0.0001 m                                                                       0.0239 g., 0.00001 m                                    BTAT-4    BTOD-3      BTAT-4                                             PIB-1B                                                                             0.2393 g., 0.0001 m                                                                     0.2446 g., 0.0001 m                                                                       0.1196 g., 0.00005 m                                    BTAT-4    BTOD-3      BTAT-4                                             PIB-1C                                                                             0.2393 g., 0.0001 m                                                                     0.2446 g., 0.0001 m                                                                       0.2393 g., 0.0001 m                                     BTAT-4    BTOD-3      SDA-3,3                                            PIB-1D                                                                             0.2393 g., 0.0001 m                                                                     0.2446 g., 0.0001 m                                                                       0.0025 g., 0.00001 m                                    BTAT-4    BTOD-3      SDA-3,3                                            PIB-1E                                                                             0.2393 g., 0.0001 m                                                                     0.2446 g., 0.0001 m                                                                       0.0125 g., 0.00005 m                                    BTAT-4    BTOD-3      SDA-3,3                                            PIB-1F                                                                             0.2393 g., 0.0001 m                                                                     0.2446 g., 0.0001 m                                                                       0.025 g., 0.0001 m                                      BTAT-5    BTOD-4                                                         PIB-2                                                                              0.2268 g., 0.00005 m                                                                    0.2289 g., 0.00005 m                                                                      none                                                    BTAT-5    BTOD-3                                                         PIB-3                                                                              0.4524 g., 0.0001 m                                                                     0.2446 g., 0.0001 m                                                                       none                                                    BTAT-4    BTOD-4                                                         PIB-4                                                                              0.2262 g., 0.00005 m                                                                    0.2290 g., 0.00005 m                                                                      none                                                    SDA-3,3   BTOD-3                                                         PIB-5                                                                              0.0496 g., 0.0002 m                                                                     0.4892 g., 0.0002 m                                                                       none                                                    SDA-3,3   BTOD-4                                                         PIB-6                                                                              0.0248 g., 0.0001 m                                                                     0.4584 g., 0.0001 m                                                                       none                                                    BTAT-4    BTCA                                                           PIB-7                                                                              0.4772 g., 0.0002 m                                                                     0.0644 g., 0.0002 m                                                                       none                                                    BTAT-5    BTCA                                                           PIB-8                                                                              0.4524 g., 0.0001 m                                                                     0.0322 g., 0.0001 m                                                                       none                                                    BTAT-4                MTA                                                PIB-9                                                                              0.5011 g., 0.00021 m                                                                    none        0.0403 g., 0.00014 m                                    BTAT-5                MTA                                                PIB-10                                                                             0.4072 g., 0.00009 m                                                                    none        0.0173 g., 0.00006 m                                    BTAT-6    BTOD-5                                                         PIB-11                                                                             0.2606 g., 0.0001 m                                                                     0.2636 g., 0.0001 m                                                                       none                                                    BTAT-7    BTOD-5                                                         PIB-12                                                                             0.2460 g., 0.00005 m                                                                    0.2476 g., 0.00005 m                                                                      none                                                    BTAT-7    BTOD-5                                                         PIB-13                                                                             0.4920 g., 0.0001 m                                                                     0.2636 g., 0.0001 m                                                                       none                                                    BTAT-6    BTOD-6                                                         PIB-14                                                                             0.2606 g., 0.0001 m                                                                     0.4952 g., 0.0001 m                                                                       none                                                    DAPB-3,3  BTOD-5                                                         PIB-15                                                                             0.0584 g., 0.0002 m                                                                     0.5272 g., 0.0002 m                                                                       none                                                    DAPB-3,3  BTOD-6                                                         PIB-16                                                                             0.1922 g., 0.0001 m                                                                     0.4952 g., 0.0001 m                                                                       none                                                    BTAT-6    BTCA                                                           PIB-17                                                                             0.5212 g., 0.0002 m                                                                     0.0664 g., 0.0002 m                                                                       none                                                    BTAT-7    BTCA                                                           PIB-18                                                                             0.4920 g., 0.0001 m                                                                     0.0322 g., 0.0001 m                                                                       none                                                    BTAT-6                MTA                                                PIB-19                                                                             0.5212 g., 0.0002 m                                                                     none        0.0384 g., 0.000133 m                                   BTAT-7                MTA                                                PIB-20                                                                             0.4920 g., 0.0001 m                                                                     none        0.0192 g., 0.000067 m                              __________________________________________________________________________

D. Preparation of Polyimides By Melt Reaction:

Small portions of the mixtures prepared in C. above were placed betweenglass slides and then the slides were dropped onto a preheated,electronically thermostatically controlled metal block. The samples wereobserved for 15 minutes and then removed. Observations in meltingbehavior, rehardening and solubility in m-cresol are given in Table III.Then the temperature of the metal block was raised and similarobservations were made both on the samples preheated for 15 minutes andonnew samples. These observations are also given in Table III. Thesuffix M designates the polymer as prepared by a melt reaction.

                                      TABLE III                                   __________________________________________________________________________    Data and Observations on the Preparation of PIB-Type Polyimides by Melt       Reactions                                                                                  Observations                                                          T.sub.1° , T.sub.2°                                                                     (sample from T.sub.1° )                                                              New Sample at                      Polymer                                                                            ° C at T.sub.1°                                                                         T.sub.2°                                                                             T.sub.2°                    __________________________________________________________________________                 partial melt, hard in 2                                                                     partial melt, hard in 20                                                                    complete melt, hard in 3             PIB-1-M                                                                            265 , 300                                                                             min., swollen in hot m-                                                                     min., slightly swollen in                                                                   min., swollen in hot m-                           cresol        hot m-cresol  cresol                                            partial melt, hard in 5                                                                     partial melt, hard in 15                                                                    complete melt, hard in 5             PIB-2-M                                                                            265 , 300                                                                             min., swollen in hot m-                                                                     min., swollen in hot m-                                                                     min., swollen in hot m-                           cresol        cresol        cresol                                            slightly melted, rehardened                                                                 partial melt, hard in 20                                                                    complete melt, hard in 5             PIB-3-M                                                                            265 , 300                                                                             immediately, swollen in hot                                                                 min., swollen in hot m-                                                                     min., slightly swollen in                         m-cresol      cresol        hot m-cresol                                      complete melt with applied                                                                  partial melt, hard in 20                                                                    complete melt, hard in 5             PIB-4-M                                                                            265 , 300                                                                             pressure, hard in 10 min.,                                                                  min., swollen in hot m-                                                                     min., slightly swollen in                         soluble in hot m-cresol                                                                     cresol        hot m-cresol                                      complete melt, hard in 5                                                                    partial melt, hard in 15                                                                    complete melt, bubbled, hard         PIB-5-M                                                                            265 , 300                                                                             min., swollen in hot m-                                                                     min., swollen in hot m-                                                                     in 15 min., swollen in hot                        cresol        cresol        m-cresol                                          complete melt, hard in 5                                                                    partial melt, hard in 20                                                                    complete melt, bubbled, hard         PIB-6-M                                                                            265 , 300                                                                             min., swollen in hot m-                                                                     min., swollen in hot m-                                                                     in 10 min., swollen in hot                        cresol        cresol        m-cresol                                          complete melt, bubbled, hard                                                                complete melt, bubbled, hard                                                                complete melt, bubbled, hard         PIB-7-M                                                                            265 , 300                                                                             in 5 min., partially solu-                                                                  in 25 min., swollen in hot                                                                  in 90 min., swollen in hot                        ble in hot m-cresol                                                                         m-cresol      m-cresol                                          partial melt, hardened imme-                                                                slow partial melt, hard in                                                                  complete melt, bubbled, hard         PIB-8-M                                                                            265 , 300                                                                             diately, swollen in hot m-                                                                  25 min., slightly swollen in                                                                in 5 min., slightly swollen                       cresol        hot m-cresol  in hot m-cresol                                   partial melt, hard in 3                                                                     slight melt, hard in 5 min.,                                                                partial melt, bubbled, hard          PIB-9-M                                                                            265 , 300                                                                             min., swollen in hot m-                                                                     swollen in hot m-cresol                                                                     in 5 min. swollen in hot                          cresol                      m-cresol                                          partial melt, hard in 3                                                                     slight melt, hard in 5 min.,                                                                partial melt, hard in 5              PIB-10-M                                                                           265 , 300                                                                             min., soluble in hot m-                                                                     swollen in hot m-cresol                                                                     min., swollen in hot m-                           cresol                      cresol                                            complete melt, bubbled,                                                                     softened, remained elastic                                                                  complete melt, bubbled,              PIB-11-M                                                                           225 , 300                                                                             hard in 15 min.                                                                             for 90 min.   elastic for 90 min.                               complete melt, bubbled,                                                                     complete melt, bubbled,                                                                     complete melt, bubbled,              PIB-12-M                                                                           225 , 300                                                                             hard in 10 min.                                                                             elastic for 90 min.                                                                         elastic for 90 min.                               complete melt, bubbled,                                                                     complete melt, remained                                                                     complete melt, bubbled,              PIB-13-M                                                                           225 , 300                                                                             hard in 20 min.                                                                             elastic for 90 min.                                                                         elastic for 90 min.                               complete melt, bubbled,                                                                     complete melt, remained                                                                     complete melt, bubbled,              PIB-14-M                                                                           225 , 300                                                                             elastic, not hard in 1 hour                                                                 elastic for 90 min.                                                                         elastic for 90 min.                               complete melt, bubbled,                                                                     slightly melted, hard in                                                                    complete melt, bubbled,              PIB-15-M                                                                           225 , 300                                                                             hard in 6 min.                                                                              30 min.       hard in 20 min.                                   complete melt, bubbled,                                                                     partial melt, bubbled,                                                                      complete melt, bubbled,              PIB-16-M                                                                           225 , 300                                                                             hard in 10 min.                                                                             elastic for 90 min.                                                                         elastic for 90 min.                               complete melt, bubbled,                                                                     complete melt, few bubbles,                                                                 complete melt, bubbled,              PIB-17-M                                                                           225 , 300                                                                             hard in 40 min.                                                                             elastic for 90 min.                                                                         elastic for 90 min.                               complete melt, bubbled,                                                                     complete melt, elastic for                                                                  complete melt, bubbled,              PIB-18-M                                                                           225 , 300                                                                             hard in 30 min.                                                                             90 min.       elastic for 30 min.                               complete melt, bubbled,                                                                     slightly melted, elastic                                                                    complete melt, few bubbles,          PIB-19-M                                                                           225 , 300                                                                             hard in 1 hour                                                                              for 90 min.   hard in 30 min.                                   complete melt, hard in                                                                      partial melt, hard in 1                                                                     complete melt, bubbled,              PIB-20-M                                                                           225 , 300                                                                             1 hour        hour          elastic for 2 hours                  __________________________________________________________________________

E. Preparation of Polyimides By Solution Reactions:

Weighed samples (0.25 g.) of each of the mixtures prepared in C. abovewereadded to 2.5 ml. of solvent and allowed to stand at ambienttemperature for24 hours with occasional swirling. Then the samples weretreated to one of the heating schedules given below.

Heating Schedule A. The solutions were heated in an air oven at 100°C.for 15 minutes. Precipitation did not occur. Then the samples wereheated in an air oven at 100° C. for 3 hours; then at 150° C. for 24hours; and finally at 200° C. for 24 hours. Then, small portions of thefilms obtained were dried in an air oven at 300° C.for 20 hours. Theobservations are given in Table IV in which the suffix S designates thepolymer as one prepared in solution. TGA data for selected PIB-typepolyimides is given in Table V.

Heating Schedule B. The soutions were heated at 50° C. for 30 minutes.Precipitation did not occur. Then the samples were heated in a forcedair oven at 40° C. for 20 hours, then at 100° C. for 4 hours. Then thesamples were removed and a small piece of the film was chipped off. Thechips were tested for softening or melting by placing them between glassslides and dropping the assembly onto a metal block preheated to 180° C.These observations are given in Table IV. Thenthe remainder of the filmswas heated at 200° C. for 72 hours and then cooled. Observations on theproducts are given in Table IV. Suffix S indicates a solution reaction.TGA data for selected PIB-type polyimides is given in Table V.

                                      TABLE IV                                    __________________________________________________________________________    Data and Observations on the Preparation of PIB-Type                          Polyimides in Solution                                                                  Heating                                                             Polymer                                                                            Solvent                                                                            Schedule     Observations                                           __________________________________________________________________________                   deep red smooth film, good adhesion to glass                   PIB-1-S                                                                            m-cresol                                                                           A    vessel.                                                                       very dark red smooth film, better adhesion                     PIB-1A-S                                                                           m-cresol                                                                           A    to glass than PIB-1-S                                                         very dark red smooth film, better adhesion to                  PIB-1B-S                                                                           m-cresol                                                                           A    glass vessel than PIB-1-S                                                     very dark red smooth film, better adhesion                     PIB-1C-S                                                                           m-cresol                                                                           A    to glass vessel than PIB-1-S                                                  very dark red smooth film, better adhesion                     PIB-1D-S                                                                           m-cresol                                                                           A    to glass vessel than PIB-1-S                                                  very dark red smooth film, better adhesion                     PIB-1E-S                                                                           m-cresol                                                                           A    to glass vessel than PIB-1-S                                                  very dark red smooth film, less adhesion                       PIB-1F-S                                                                           m-cresol                                                                           A    to glass vessel than PIB-1-S                                                  deep red smooth film, good adhesion to                         PIB-2-S                                                                            m-cresol                                                                           A    glass vessel                                                                  deep red smooth film, good adhesion to                         PIB-3-S                                                                            m-cresol                                                                           A    glass vessel                                                                  lighter red smooth film, good adhesion                         PIB-4-S                                                                            m-cresol                                                                           A    to glass vessel                                                               deep red smooth film, good adhesion to                         PIB-5-S                                                                            m-cresol                                                                           A    glass vessel                                                                  lighter red smooth film, good adhesion to                      PIB-6-S                                                                            m-cresol                                                                           A    glass vessel                                                                  lighter red smooth film, good adhesion to                      PIB-7-S                                                                            m-cresol                                                                           A    glass vessel                                                                  very deep red smooth film, good adhesion                       PIB-8-S                                                                            m-cresol                                                                           A    to glass vessel                                                               dark-brown smooth film, good adhesion to                       PIB-9-S                                                                            m-cresol                                                                           A    glass vessel                                                                  dark-brown smooth film, with small amount of                   PIB-10-S                                                                           m-cresol                                                                           A    very fine particles, good adhesion to glass                                   vessel                                                                        H100: good yellow film; H180: melted,                          PIB-11-S                                                                           dioxane                                                                            B    bubbled, hardened in 10 sec.; H200: foamed,                                   tough film                                                                    H100: some solid in yellow film; H180:                         PIB-12-S                                                                           dioxane                                                                            B    melted, bubbled, hardened in 20 min.; H200:                                   foamed, tough film                                                            H100: some solid in yellow film; H180:                         PIB-13-S                                                                           dioxane                                                                            B    melted, bubbled, hardened in 1 min.; H200:                                    foamed, tough film                                                            H100: good yellow film; H180: melted,                          PIB-14-S                                                                           dioxane                                                                            B    bubbled, hardened in 1 min.; H200: foamed,                                    tough film                                                                    H100: good yellow film; H180: melted,                          PIB-15-S                                                                           dioxane                                                                            B    bubbled, hardened in 1 min.; H200: foamed,                                    tough film                                                                    H100: good yellow film; H180: melted,                          PIB-16-S                                                                           dioxane                                                                            B    bubbled, hardened in 1 min.; H200: foamed,                                    tough film                                                                    H100: good yellow film; H180: melted,                          PIB-17-S                                                                           dioxane                                                                            B    bubbled, hardened in 1 min.; H200: foamed,                                    tough film                                                                    H100: good yellow film; H180: melted,                          PIB-18-S                                                                           dioxane                                                                            B    bubbled, hardened in 1 min.; H200: foamed                                     tough film                                                                    solution gelled in 1/2 hr.; H100: good yellow                  PIB-19-S                                                                           dioxane                                                                            B    film; H180: softened, not hard in 1 hr.;                                      H200: few bubbles, tough film                                                 solution gelled in 1/2 hr.; H100: good yellow                  PIB-20-S                                                                           dioxane                                                                            B    film; H180: softened, not hard in 1 hr.;                                      H200: few bubbles, tough film                                  __________________________________________________________________________

                                      TABLE V                                     __________________________________________________________________________    TGA Data for Selected PIB-Type Polyimides                                     Atmos-   TGA: Percent Residue at                                              Polymer                                                                            phere                                                                             200° C                                                                     300° C                                                                     400° C                                                                     500° C                                                                     600° C                                                                     700° C                                                                     800° C                                __________________________________________________________________________    PIB-1-S                                                                            Air 100  98 94  89  67  0   0                                            PIB-1F-S                                                                           Air 100  99 95  92  73  0   0                                            PIB-4-S                                                                            Air 100 100 97  89  70  12  0                                            PIB-8-S                                                                            Air 100 100 97  93  78  0   0                                            PIB-9-S                                                                            Air 100  98 92  89  70  0   0                                            PIB-11-S                                                                           Air 100 100 99+ 99  76  0   0                                            PIB-17-S                                                                           Air 100 100 99  98  83  10  0                                            PIB-19-S                                                                           Air 100 100 98  97  82  13  0                                            __________________________________________________________________________

F. Coating of Substrates:

Solutions PIB-17-S and PIB-19-S were coated on various substrates eitherbyapplying the solution with a small camel's hair brush or by dipping,and then cured by heating the coated articles in a forced air oven at80° C. for 20 hours, 100°-110° C. for 3 hours and then 200° C. for 20hours. Substrates coated were stainless steel and aluminum panels, 100pores/inch and 20 pores/inch reticulated polyurethane foam, 1.5 oz./ft.²random glass mat, copper wire No. 24,wood dowel (charred during cure),and asbestos board. Bubbling occurred on the surface of many of thesamples prepared from PIB-17-S. Very little bubbling occurred to thecoatings prepared from PIB-19-S.

EXAMPLE 8

(a) Synthesis of Propargyl-Terminated Oligomeric Polyimide (BTPA-1).Reaction of BTCA, CDA and Propargyl Amine (2:1:2).

In a m-cresol:benzene azeotropic apparatus was placed a solution of BTCA(29.001 g., 0.09 mole) in 200 ml. of m-cresol and 50 ml. of benzene. Themixture was warmed to approximately 50° C. and a solution of ODA (9.011g., 0.045 mole) in 150 ml. of m-cresol was added, forming a slightamount of yellow precipitate. After 10 minutes, a solution of propargylamine (5 g., 0.0908 mole) in 50 ml. of m-cresol was added and thesolutionheated to reflux. During 2 hours of reflux, 3.3 ml. of water wascollected.After cooling, the deep red solution was concentrated on arotary flash evaporator. A small sample was removed for analysis andapproximately 5 mg. of t-butyl catechol was added to the bulk of theresidue, which was vacuum-dried at 100° C. for 30 hours, and then at150° C. for 12 hours, to give sample A, 37.850 g. (95%) as a dark-brownsolid. It softened at 270° C.; partially melted between 280°-300° C.,but quickly rehardened at 300° C.

Analysis: Calc'd. for C₅₂ H₂₆ N₄ O₁₁ : C, 70.75; H, 2.97; N, 6.35; O,19.94. Found: C, 70.84; H, 3.13; N, 6.31; O, --.

(b) Polymerization of BTPA-1.

A sample of BTPA-1 was mixed with about 5% by weight of Cu₂ Cl₂ (cuprouschloride) and spread on a hot plate preheated to the melting point ofthe BTPA-1. The sample was open to air. An infusible, insoluble polymerwas obtained due to the oxygen coupling of the acetylene terminalgroups.

EXAMPLE 9

(a) Preparation of Phenolic-Terminated Oligomeric Polyimide (BTAP-1).Reaction of BTCA, ODA and p-Aminophenol (2:1:2).

In the m-cresol:benzene azeotropic apparatus was placed a solution ofBTCA (3.222 g., 0.01 mole) in 25 ml. of m-cresol and 15 ml. of benzene.After warming to 50° C., a solution of ODA (1.001 g., 0.005 mole) in 15ml. of m-cresol was added, forming an immediate yellow precipitate.Further heating did not dissolve the precipitate, and, after 10 minutes,aslurry of freshly purified p-aminophenol (m.p. 190°-193° C.; 1.019 g.,0.01 mole) in 10 ml. of m-cresol was added. At reflux, thesoliddissolved forming an orange solution. During 2 hours of reflux,0.20 ml. ofwater was collected and a precipitate formed. Then, thesolvents were removed on a rotary flash evaporator and the residue wasvacuum-dried at 170° C., yielding a yellow solid, 4.907 g. (99%). Itsinfrared spectrum was consistent with the structure expected for thecompound. It softened slightly at 50° C., was almost completely meltedat 265° -280° C.; and rehardened at 283° C. It was soluble in hotm-cresol, hot DMAC and hot sulfolane.

Analysis: Calc'd. for C₅₈ H₃₀ N₄ O₁₃ : C, 70.30; H, 3.05; N, 5.65; O,20.99. Found: C, 70.04; H, 3.01; N, 5.73; O, --.

(b) Polymerization of BTAP-1.

A mixture of BTAP-1 with about 10-12% paraformaldehyde and 1-5% limecures into an insoluble, intractable polymer when heated at the meltingpoint ofBTAP-1 on a hot plate.

EXAMPLE 10

(a) Preparation of Phenol-Terminated Oligomeric Polyimide (BTAP-4).Reaction of BTCA, SDA-3,3 and p-Aminophenol (5:4:2).

According to the m-cresol:benzene technique there was allowed to reactBTCA(6.4446 g., 0.02 mole), SDA-3,3 (3.9730 g., 0.016 mole) andp-aminophenol (0.8730 g., 0.008 mole). There was obtained 10.0418 g.(95%) of a pale yellow powder (BTAP-4) which was soluble in m-cresol,DMAC and sulfolane. In hot dioxane BTAP-4 formed a separate oily layer.On a Fisher-Johns melting point apparatus BTAP-4 softened at 210° C.,melted at 240°-260° C. and did not harden on being heated at 300° C. for40 minutes. The lowest temperature at which a sample would meltcompletely when dropped onto the preheated stage was 250° C.

Analysis: Calc'd. for C₁₄₅ H₇₂ N₁₀ O₃₅ S₄ : C, 65.90; H, 2.75; N, 5.30;O, 21.19; S, 4.85. Found: C, 65.45; H, 2.88; N, 4.99; O, --; S, --. C,65.43; H, 2.95; N, 5.31; O, --; S, --.

(b) Polymerization of BTAP-4.

A mixture of BTAP-4 with about 10-12% paraformaldehyde and 1-5% limecures into an insoluble, intractable polymer when heated at the meltingpoint ofBTAP-4 on a hot plate.

(c) Preparation of Aldehyde-Terminated Oligomer.

When an equivalent molar quantity of p-aminobenzaldehyde, NH₂ C₆ H₄ CHO(0.968 g.) is used instead of the p-aminophenol of (a) of thisExample,the corresponding aldehyde-terminated oligomeric imide is obtained.

Similarly, when an equivalent molar amount ofp-aminobenzylidene-aniline, NH₂ C₆ H₄ CH=NC₆ H₅ (1.568 g.) is usedinstead ofthe p-aminophenol of (a) of this Example, the correspondingSchiff base-terminated oligomer is obtained. The amino-aryl Schiff baseswere readily prepared by the procedure give by Rossi in Gazz. chim.,Ital., 44,263 (1966).

(d) Coupling of Schiff Base-Terminated Oligomer.

The Schiff base-terminated oligomers as in (c) of this Example couplesimilarly to the nitrile terminated oligomers of Example 6. They couplereadily when heated in the range of 200°-300° C. for 30 minutes to 2hours, depending on the nature of the oligomer and of the Schiff basetermini. The coupling reaction is accelerated markedly by the additionof catalytic quantities of Lewis acid salts, from about 0.15 to about 3weight percent, such as AlCl₃, SbCl₃, SbCl₅ or any of the numerous Lewisacid salts well-known as alkylation, isomerization or polymerizationcatalysts. For reasons of economy and relative ease of handling, zincchloride, zinc sulfate, and the copper salts are preferred as couplingcatalysts for the Schiff base-terminated oligomeric polyimides.

EXAMPLES 11-56

A. Preparation of Imide Oligomers

(a) Preparation of Aromatic Nitrile-Terminated Oligomeric Polyimide(BTAN-2). Reaction of 3,3',4,4'-Benzophenonetetracarboxylic AcidDianhydride (BTCA), 4,4'-Oxydianiline (ODA) and 4-Aminobenzonitrile (AN)(2:1:1).

In the m-cresol:benzene azeotropic apparatus there was placed a solutionof3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTCA) (3.222g., 0.01 mole) in 25 ml. m-cresol and 15 ml. benzene. The mixture waswarmed to approximately 50° C. and a solution of 4,4'-oxydianiline (ODA)(1.001 g., 0.005 mole) in 15 ml. of m-cresol was added, giving animmediate yellow precipitate. After 15 minutes, a solution of4-aminobenzonitrile (AN) (1.299 g., 0.011 mole) in 10 ml. of m-cresolwas added. During 2 hours of refluxing the solution became orange and0.25 ml of water was collected. Precipitation did not occur. Aftercooling, the solvents were removed on a rotary flash evaporator and theresidue was vacuum-dried at 100° C. to yield 5.177 g. (102%) ofphenylnitrile-terminated oligomeric polyimide based on BTCA (BTAN-2). OnaFisher-Johns melting point apparatus, 230° C. was the lowesttemperature at which it softened before rehardening immediately. It wassoluble in hot m-cresol, slightly soluble in hot dimethyl acetamide(DMAC), and insoluble in hot acetone. A sample of BTAN-2 was postheatedinnitrogen at 300° C. for 24 hours, and its TGA in nitrogen of sampleBTAN-2-H300, showed an inflection point at 410° C.

Analysis: Calc'd. for C₆₀ H₂₈ N₆ O₁₁ : C, 71.43; H, 2.80; N, 8.03; O,17.44 Found: C, 70.83; H, 2.81; N, 7.77; O--. Found: C, 71.22; H, 2.86;N, 7.93; O,--(dried at 140° C.)

(b) Preparation of Aromatic Nitrile-Terminated Oligomeric Polyimide(BTAN-3). Reaction of BTCA, 3,3'-Sulfonyldianiline (SDA-3,3) and AN(9:8:2).

In the m-cresol:benzene azeotropic apparatus there was placed a solutionofBTCA; (2.1750 g., 0.00675 mole) in 25 ml. of m-cresol and 10 ml. ofbenzene. The solution was warmed to approximately 70° C. and a solutionof AN (0.1773 g., 0.0015 mole) in 10 ml of m-cresol was added over about20 minutes. After stirring at approximately 70° C. for 15 minutes, asolution of 3,3'-sulfonyldianiline (SDA-3,3) (1.4899 g., 0.0060 mole) in15 ml. of m-cresol was added and the solution was heated to reflux for 3hours, during which time, 0.3 ml. of water was collected; then thebenzene was distilled off and after cooling to room temperature, thesolution was added dropwise slowly to 200 ml. of well-stirred methanol,to yield a light-yellow solid. The solid was filtered off, digested fourtimes in hot methanol, and dried at 40° C. for 24 hours, to give 3.40 g.(95%) of yellow product. The yield, corrected for about 2% retainedm-cresol, was 93.5%. The oligomer partially melted at 255° C. andrehardened at 275° C.; it was soluble in m-cresol, DMAC and hotsulfolane, but insoluble in dioxane. A small sample, vacuum-dried at200° C. for 4 hours, showed a 2% loss of m-cresol, which was confirmedin its TGA in nitrogen, which also shows an inflection point in nitrogenin the 500° C. region. Its DTA in nitrogen shows an endotherm at 225° C.

Analysis: Calc'd. for C₂₆₃ H₁₂₆ N₂₀ O₆₁ S₈ : C, 65.83; H, 2.65; N, 5.84;O, 20.34; S, 5.35. Found: C, 65.29; H, 2.70; N, 5.36; O, --; S, --.

The above procedure was repeated except that the quantities used wereincreased to yield 33.0 g. (97%) of BTAN-3. The quantities used wereBTCA,21.7505 g., 0.0675 mole; SDA-3,3, 14.899 g., 0.060 mole; AN, 1.7172g., 0.0150 mole.

(c) Preparation of Aromatic Nitrile-Terminated Oligomeric Polyimide(BTAN-4). Reaction of BTCA, 1,3-Di(3-Aminophenoxy)benzene (DAPB-3,3) andAN (9:8:2).

In the m-cresol:benzene azeotropic apparatus there was placed a solutionofBTCA (2.1753 g., 0.00675 mole) in 25 ml. of m-cresol and 10 ml ofbenzene. The solution was warmed to approximately 70° C. and a solutionof AN (0.1773 g. 0.0015 mole) in 10 ml. of m-cresol was added over about20 minutes. After stirring for another 15 minutes, a solution of1,3-di(3-aminophenoxy)benzene (DAPB-3,3) (1.7540 g., 0.0060 mole) in 15mlof m-cresol was added. The solution was heated to reflux for 3 hoursand 0.2 ml of water was collected. Then the benzene was distilled off.After cooling, the clear solution was added dropwise to 200 ml ofmethanol. The precipitated solid was digested three times in hotmethanol and vacuum-dried at 70° C. to give BTAN-4, as a light-yellowsolid, 3.4g. (88%).

The infrared spectrum (KBr disc) of BTAN-4 is given in FIG. 29; it wassoluble in m-cresol, DMAC, sulfolane, dioxane; because a paste inmethylene chloride, swelled in chloroform and was insoluble inacetonitrile. BTAN-4 softened at 180° C., melted over the range of197°-218° C., thickened above 290° C., but did not harden within 20minutes at 300° C., although it did darken somewhat. For the sampledried at 70° C., the DTA in nitrogen showed a melting endotherm at about180° C.

A sample of BTAN-4, vacuum-dried at 200° C., to eliminate volatiles,wassubmitted for analysis.

Analysis: Calc'd. for C₃₀₅ H₁₅₈ N₂₀ O₆₁ : C, 72.13; H, 3.14; N, 5.52; O,19.22. Found: C, 72.41; H, 3.28; N, 5.11; O, --.

(d) Synthesis of Allyl-Terminated Oligomeric Polyimide (BTAA-3).Reaction of BTCA, ODA and Allylamine (2:1:2).

In the m-cresol:benzene azeotropic apparatus, there was placed asolution of BTCA (3.222 g., 0.01 mole) in 25 ml. of m-cresol and 15 ml.of benzene.The solution was warmed to approximately 60° C. and asolution of ODA (1.001 g., 0.005 mole) in 15 ml. of m-cresol was added,forming an immediate yellow precipitate which dissolved on heatingfurther for 5 minutes. Then, a solution of allylamine (0.629 g., 0.011mole) in 10 ml ofm-cresol was added, after which the solution was heatedto reflux; during 2hours of reflux 0.25 ml. of water was collected.After cooling, the solution was made up to 80 ml. with added benzene,and it was divided intotwo 40 ml. portions.

The first 40-ml. fraction was added to 250 ml. of methanol and thenstirredfor 1 hour. This solid material was isolated by centrifuging anddried in avacuum oven at 80° C. for 36 hours, yielding a yellow solid(A), 1.87 g. (84%).

The second 40-ml. fraction was evaporated on a rotary flash evaporatorand the residue was dried in a vacuum oven at 80° C., yielding ayellowsolid (B), 2.306 g. (104%). Sample B softened at 130° C., wasnearlycompletely molten at 200°-300° C., darkened in 10 minutes at 230°C., was soluble in hot m-cresol, slightly soluble in hot DMAC,andinsoluble in acetone.

Analysis: Calc'd. for C₅₂ H₃₀ N₄ O₁₁ : C, 70.42; H, 3.41; N, 6.32; O,19.85. Found: C, 70.99; H, 3.79; N, 6.47; O, --.

A sample of BTAA-3B was postheated in nitrogen at 300° C. for 24 hours,and its TGA in nitrogen, at 10° C./minute, showed an inflection point at360° C.

(e) Preparation of Aliphatic Nitrile-Terminated Oligomeric Polyimide(BTBN-1). Reaction of BTCA, ODA and 4-Aminobenzyl Cyanide (BN) (2:1:2).

In the m-cresol:benzene azeotropic apparatus was placed a solution ofBTCA (3.222 g., 0.01 mole) in 25 ml. m-cresol and 15 ml. of benzene. Themixture was warmed to approximately 50° C. and a solution of ODA (1.001g., 0.005 mole) in 15 ml. of m-cresol was added, giving an immediateyellow precipitate. After refluxing for 15 minutes, a solution ofaminobenzyl cyanide (BN) (1.454 g., 0.011 mole) in 10 ml. of m-cresolwas added. The precipitate dissolved quickly. During 11/2 hours ofreflux,0.30 ml. of water was collected and a precipitate formed. Thensodium acetate (0.041 g., 0.0005 mole) was added and reflux wascontinued for another hour, and another 0.05 ml. of water was collected.After cooling, the solvents were removed on a rotary flash evaporatorand the residue wasdried in a vacuum oven at 100° C., the yield was5.170 g. (˜100%). Its infrared spectrum was consistent with the expectedstructure. Benzylcyanide-terminated oligomeric polyimide based on BTCA(BTBN-1) softened at 200° C., was almost completely melted by 290° C.and rehardened rapidly at 300° C. Also, it was soluble in hot m-cresol,slightly soluble in hot DMAC, and insoluble in acetone. A sample driedat 300° C. was also submitted for analysis.

Analysis: Calc'd. for C₆₂ H₃₂ N₆ O₁₁ : C, 71.81; H, 3.11; N, 8.11; O,16.97. Found (B): C, 70.28; H, 3.22; N, 8.12; O, --. (dried at 300° C.)

The TGA in nitrogen on the sample dried at 300° C. showed an inflectionpoint of 360° C.

(f) Preparation of Aliphatic Nitrile-Terminated Oligomeric Polyimide(BTBN-3). Reaction of BTCA, SDA-3,3 and BN (9:8:2).

According to the azeotropic procedure used in (b) above, BTCA, (2.1752g., 0.00675 mole), BN (0.1982 g., 0.0015 mole) and SDA-3,3 (1.4898 g.,0.0060 mole) were allowed to react. There was obtained 3.27 g. (91%) ofa light-yellow solid (BTBN-3). The yield, corrected for approximately 1%retained m-cresol, was 89%.

The oligomer melted at 250°-26° C., and rehardened at 290° C. It wassoluble in m-cresol, DMAC and hot sulfonlane but insoluble in dioxane.

A small portion, vacuum-dried at 200° C. for 4 hours showed a 1% loss ofretained m-cresol, which was confirmed in its TGA in nitrogen which alsoshowed an inflection point in the 500° C. region.

The above procedure was repeated except that the quantities used weresuch as to yield a larger amount of product: BTCA, 21.750 g., 0.0675mole; SDA-3,3, 14.899 g., 0.060 mole; BN, 1.982 g., 0.0150 mole. TheBTBN-3 obtained from this reaction amounted to 34.8 g. (96%).

Analysis: Calc'd. for C₂₆₅ H₁₃₀ N₂₀ C₆₁ S₈ : C, 65.94; H, 2.72; N, 5.80;O, 20.22; S, 5.32. Found: C, 65.18; H, 2.65; N, 5.71; O --S, --.

(g) Preparation of Aliphatic Nitrile-Terminated Oligomeric Polyimide(BTBN-4). Reaction of BTCA, DAPB-3,3 and BN (9:8:2).

According to the procedure used in (c) above to prepare BTAN-4, BTCA(2.1753 g., 0.00675 mole), BN (0.1982 g., 0.0015 mole) and DAPB-3,3(1.7540 g., 0.0060 mole) were allowed to react to afford, aftervacuum-drying at 70° C., BTBN-4, 3.8 g. (97%) as a light-yellow solid.BTBN-4 was soluble in m-cresol, DMAC, sulfolane and dioxane. Itwaspartially soluble in hot chloroform and hot methylene chloride, andwas insoluble in acetonitrile.

On a Fisher-Johns melting point apparatus, BTBN-4 softened at 135° C.,melted at 196°-215° C., thickened above 235° C. and remelted at 255° C.It did not reharden when held for 1/2 hour at 300° C. A sample ofBTBN-4, vacuum-dried at 200° C., was submitted for analysis.

Analysis: Calc'd. for C₃₀₇ H₁₆₂ N₂₀ O₆₁ : C, 72.20; H,3.20; N, 5.49; O,19.11. Found: C, 72.21; H, 3.15; N, 5.44; O, --.

(h) Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-1).Reaction of BTCA, ODA and m-Aminostyrene (AS) (2:1:2).

In the m-cresol:benzene azeotropic apparatus was placed a solution ofBTCA (3.222 g., 0.01 mole) in 25 ml. of m-cresol and 10 ml. of benzene.After warming to approximately 70° C., a solution of ODA (1.001 g.,0.005mole) in 15 ml. of m-cresol containing 2 mg. of t-butyl catecholwas added,forming an immediate yellow precipitate. After heating for 15minutes, a solution of m-aminosytrene (AS) (1.192 g., 0.01 mole, SaponLaboratories) in 10 ml. of m-cresol was added and the solution washeated to reflux, forming a homogeneous solution. After 1 hour ofreflux, a precipitate began to form. After 2 hours of reflux, duringwhich 0.25 ml. of water wascollected, the reaction mixture was cooledand poured into 250 ml. of methanol. After stirring for several hours,the solid material was filtered off, washed with methanol andvacuum-dried at 40° C. for 18 hours. The sample still had a distinctodor of m-cresol. A small portion was removed and vacuum-dried at 200°C. for 24 hours to give fraction A whose infrared spectrum was recorded.The remainder of thematerial was finely divided and stirred with 50 ml.of ether, and dried at 40° C. to afford 4.0402 g. (80%) of a yellowpowder, fraction B. The infrared spectrum of sample A was substantiallythe same as that of sample B.

Sample A softened at 220° C.; was partially molten at 250° C.whenpressure was applied; was almost completely molten at 300° C. whenpressure was applied; and rehardened (cured) to a granular solid after25 minutes at 300° C. Sample A was slightly soluble in hot m-cresol.

Sample B softened at 70° C.; was nearly completely molten at 225° C.with applied pressure; and hardened (cured) to a granular solid at 250°C. Sample B was soluble in hot m-cresol, and virtually insoluble insulfolane, DMAC and toluene.

Analysis: Calc'd. for C₆₂ H₃₄ N₄ O₁₁ : C, 73.66; H, 3.39; N, 5.54; O,17.41. For A Found: C, 73.21; H, 3.67; N, 5.79; O, --.

A portion of sample B was postheated in nitrogen at 300° C. for 24hours, and a TGA performed in nitrogen at 10° C. minute, showed aninflection point of 410° C.

(i) Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-3).Reaction of BTCA, DAPB-3,3 and AS (8:7:2).

In the m-cresol:benzene azeotropic apparatus fitted with provisions fora nitrogen sweep, was placed a warm solution of BTCA (1.2889 g., 0.004mole)in 25 ml. of m-cresol and 10 ml. of benzene containing 1-2 mg. oft-butyl catechol. Then a solution of AS (1.1192 g., 0.01 mole) in 5 ml.of m-cresol was added and the solution was then stirred and heated atapproximately 70° C. for 15 minutes. Then a solution of DAPB-3,3 (1.023g., 0.0035 mole) in 10 ml. of m-cresol was added and the solution heatedto reflux which was maintained for 4 hours, during which time,approximately 1.5 ml. of water was collected. Then the benzene wasdistilled off. After cooling to ambient temperature, the slightly hazysolution was added dropwise to 150 ml. of methanol. The solid wasfilteredoff and washed three times in 30 ml. of boiling methanol, whichcontained atrace of t-butyl catechol, for 15 minutes each time, then itwas given a final wash with inhibitor-free boiling methanol. The yellowsolid was filtered and vacuum-dried at room temperature for two days togive BTAS-3,1.782 g. (78%) as a yellow solid. Its TGA in nitrogen at 10°C./minute showed the retention of m-cresol solvent.

On a Fisher-Johns melting point block, it melted at 190°-195°C.,hardened at 205° C., resoftened and remelted at 210°-233° C., andrehardened at 268° C. Its DTA at 20° C./minute showed a meltingendotherm at 183° C. BTAS-3 was soluble in dioxane, m-cresol, DMAC andsulfolane; it swelled in tetrahydrofuran, styrene, divinylbenzene andtoluene, and was insoluble inmethyl ethyl ketone.

A portion of BTAS-3 was vacuum dried at 200° C. for 36 hours andanalyzed.

Analysis: Calc'd. for C₂₇₈ H₁₄₆ N₁₆ O₅₄ : C, 72.99; H,3.22; N, 4.90; O,18.89. Found: C, 73.55; H, 3.31; N, 5.03; O, --.

(j) This oligomer (BTAS-4) is prepared in Example 3 above.

(k) Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-10R).Reaction of BTCA, 4,4'-Methylenedianiline (MDA-4,4) and AS (9:8:2).

In the m-cresol:benzene azeotropic apparatus equipped with a nitrogeninletand outlet, there was placed BTCA (21.7505 g., 0.0675 mole) in 80ml. of m-cresol and 40 ml. of benzene. The temperature of the mixturewas raised to approximately 70° C. as nitrogen was passed through theapparatus, and a solution of m-aminostyrene (AS) (1.7874 g., 0.015 mole)in 40 ml. of m-cresol containing 0.1 g. of t-butyl catechol was addedover15 minutes, and the solution was stirred for an additional 15minutes. Thena solution of 4,4'-methylenedianiline (MDA-4,4) (11.8956g., 0.060 mole) in55 ml. of m-cresol was added and the solution wasbrought to reflux. After refluxing for 3 hours, during which 2.35 ml. ofwater was collected, a copious yellow precipitate was present. Then, thebenzene was distilled off and the reaction solution was added dropwiseto methanol. The precipitated oligomer was digested three times in hotmethanol containing approximately 0.1 g. of t-butyl catechol and thenvacuum-dried at ambient temperature for 63 hours to afford BTAS-10R,32.565 g. (98.7%), whose infrared spectrum was consistent with thatexpected for the compound.

A 2.25 g. sample of BTAS-10R was washed once with methanol to remove theinhibitor to afford 2.190 g. of inhibitor-free BTAS-10, whose DTA in airshowed a slight endotherm at 150° C., followed by an exotherm at 175° C.

Analysis: Calc'd. for C₂₇₃ H₁₄₈ N₁₀ O₄₅ : C, 74.52; H,3.39; N, 5.73; O,16.36 Found: C, 73.38; H, 3.52; N, 5.84; O, 16.59.

(l) Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-11).Reaction of BTCA, 1,3-Di(4-Aminophenoxy)benzene (DAPB-3,4) and AS(9:8:2).

By the procedure used in the preparation of (k) above, there was reactedBTCA (1.8126 g., 0.00563 mole) in 25 ml of m-cresol and 20 ml ofbenzene, a solution of AS (0.14909) g., 0.00125 mole) in 10 ml. ofm-cresol containing 0.1 g. t-butyl catechol, and a solution of1,3-di(4-aminophenoxy)benzene (DAPB-3,4) (1,4617 g., 0.005 mole) in 20ml.of m-cresol. After refluxing for 5 hours, there was obtained 0.35 ml.of water and solution had not occurred. Then the benzene was distilledoff and the reaction mixture was slowly poured into methanol toprecipitate the oligomer. The oligomer was digested thred times in hotmethanol containing 0.1 g. t-butyl catechol and vacuum-dried at 40° C.to give 3.4882 g. (96.8%) of BTAS-11 as a yellow powder. A small portionof BTAS-11 was digested again in hot methanol to remove the inhibitorfor usein testing. Its infrared spectrum was consistent with thatexpected for thecompound.

The TGA in air showed the retention of about 3% m-cresol and aninflection point in the 500° C. region.

Analysis: Calc'd. for C₃₁₃ H₁₆₄ N₁₈ O₆₁ : C, 72.96; H,3.21; N, 4.89; O,18.94. Found: C, 72.22; H, 3.11; N, 4.69; O, --.

(m) Preparation of Styrene-Terminated Oligomeric Polyimide (BTAS-1).Reaction of 1,4,5,8-Naphthalenetetracarboxylic Acid Dianhydride (NTCA),DAPB-3,3 and AS (9:8:2).

According to the procedure given for (1) above, there was allowed toreact 1,4,5,8-naphthalenetetracarboxylic acid dianhydride (NTCA) (2.8369g., 0.01125 mole), DAPB-3,3 (2.9233 g., 0.01 mole) and AS (0.2979 g.,0.0025 mole). There was obtained NTAS-1 as a tan powder which partiallymelted, with darkening at 220°-260° C., rehardened at 265° C., and thendid not change up to 300° C. When a sample was placed on a Fisher-Johnsapparatus at approximately 220° C., it became completely molten by 260°C. and rehardened at about 265° C.

NTAS-1 was soluble in DMAC, m-cresol, sulfolane and concentratedsulfuric acid, and swelled in hot dioxane. Its infrared spectrum wasconsistent with that expected for the compound.

Analysis: Calc'd. for C₂₈₆ H₁₄₆ N₁₈ O₅₂ : C, 73.61; H,3.15; N, 5.40; O,17.83. Found: C, 73.74; H, 3.50; N, 5.83; O, --.

(n) Preparation of Styrene-Terminated Oligomeric Polyimide (PMAS-1).Reaction of Pyromellitic Anhydride (PMA), DAPB-3,3and AS (9:8:2).

According to the procedure given for (1) above, there was allowed toreact pyromellitic anhydride (PMA) (2.4538 g., 0.01125 mole), DAPB-3,3(2.9233 g., 0.01 mole) and AS (0.2979 g., 0.0025 mole). Completesolution did not occur during the reaction period. There was obtainedPMAS-1, which melted at 150°-210° C., rehardened at 240° C., andresoftened at 275° C., and rehardened after 20 minutes at 300° C. PMAS-1swelled in m-cresol, and was insoluble in concentrated sulfuric acid,hot DMAC, sulfolane and dioxane. Its infrared spectrum was consistentwith that expected for the compound. Its DTA in air and its TGA in airshowed solvent retention and an inflection point inthe 500° C. region.

Analysis: Calc'd. for C₂₅₀ H₁₂₈ N₁₈ O₅₂ : C, 71.22; H,3.06; N, 5.98; O,19.74. Found: C, 71.22; H, 3.22; N, 6.17; O, --

B. Dipolar Cycloaddition Reactions

In Examples 11-56, three procedures, A to C inclusive, were used topreparecycloaddition reaction products of some dipolarophilic-terminatedoligomeric polyimides prepared in (a) to (n) of Part A of this Examplewith two dipoles 1,4-benzenedinitrile oxide (BDNO) and1,4-benzenedi(phenylnitrilimine)-- (BDNI). However, basically, the threeprocedures are equivalent. Minor modifications were introduced toaccommodate the particular systems used. For example, in some cases ahighly soluble oligomer required less solvent in which to perform thereaction.

Procedure A: The acceptor was first dissolved in 18 ml. of m-cresol, bywarming if necessary. The solid dipole was added and the mixture wasstirred at ambient temperature until solution was effected. The solutionwas then placed in an air oven at 70°-80° C. for 5 to 8 days, afterwhich the temperature was raised to 200° C. for 1 day. Finally, thesamples were vacuum-dried at 200° C. for 1 day, and the weight recorded.Small samples were dried in an air oven at 200° C., 240° C. or 300° C.for 24 hours and the temperature at which they were cured designated bythe suffix, H200, H240 and H300 after the polymer number.

Procedure B: The acceptor was first dissolved in 5-10 ml. of m-cresol,by warming if necessary. Then solid dipole was added and the mixture wasstirred at ambient temperature until solution occurred, after which thesolution was then placed in an air oven at 100° C. for 24 hours, andthen at 200° C. for 48 hours. The residues were then vacuum-dried at200° C. for 24 hours and the weights recorded. Small samples were driedin an air oven at 300° C. for 24 hours andare designated as H300.

Procedure C: This procedure is a modification of Procedure B in that,aftermixing, the samples were allowed to stand at ambient temperaturefor 48 hours and then were heated to 200° C. over an 8-hour period.After drying in an air oven at 200° C. for 48 hours, the residues werevacuum-dried at 200° C. for 24 hours and the weights were recorded.

BDNI and BDNO were prepared as follows:

Synthesis of 1,4-Benzenedi(phenylnitrilimine) p-C₆ H₄ (C═NNC₆ H₅)₂, BDNI

1. Intermediate Terephthaloylphenylhydrazide Chloride, ##STR17##

A mixture of 5.8 g. (0.016 mole) of terephthaloylphenylhydrazide, (m.p.265° C.), 7.5 g. (0.036 mole) phosphorous pentachloride in 60 ml.anhydrous ether was heated under reflux for twenty-four hours duringwhichtime the mixture remained heterogeneous. Then 20 g. phenol (0.212mole) in 20 ml. ether was added to the mixture, followed by the slowaddition of 30ml. (0.74 mole) of methanol and allowed to cool to roomtemperature. The yellow crystals which formed were separated by thefiltration. The filtrate was concentrated at 50° C. until more crystalsappeared; these were isolated by filtration. The crude product wasrecrystallized from benzene, yielding 2.14 g. (35.0%); m.p. 216°-217° C.Its infrared spectrum showed the C═N absorption at 6.3 μ; the ammidepeak, ##STR18##at 5.9μ was not present.

Analysis: Calc'd. for C₂₀ H₁₆ Cl₂ N₄ : C, 62.66; H, 4.20; N, 14.62; Cl,18.52. Found: C, 62.92; H, 4.32; N, 14.49; Cl, 18.30.

2. Synthesis of BDNI from BCNI

To 0.2 g. of BCNI in 2 ml. DMAC there was added 0.12 g. Et₃ N and themixture allowed to react with stirring at room temperature for twohours. Then 5 ml. of water was added and the resulting precipitateremoved by filtration, washed with distilled water and dried in a vacuumoven at 30° C.; yield of brown powder, 0.152 g. (˜100%); m.p. 180°-185°C. (with resinification).

BDNI is used within 72 hours after its preparation.

Synthesis of 1,4-Benzenedinitrile Oxide BDNO

1. Intermediate Terephthaldehyde Dioxime, p-C₆ H₄ (CH═NOH)₂

Into a 2-liter Erlenmeyer flask were place 45 g. (0.66 mole ofhydroxylamine . HCl dissolved in 237 ml. of water and 26.4 g. (0.66mole) of sodium hydroxide dissolved in 150 ml. of water; this mixturewas thoroughly agitated. Then 40.2 g. (0.3 mole) of terephthaldehyde,dissolved in 300 ml. of ethanol was added to the mixture, which remainedclear for a few seconds, then a large amount of white precipitateformed. The mixture was brought to reflux on a steam bath, then 200 ml.of 95% ethanol was added to dissolve the precipitate, and reflux wascontinued for 30 minutes, after which the mixture was cooled in anice-water bath, and the white crystals which precipitated were recoveredby filtration. The crude dioxime was recrystallized from a 55% ethanol45% water solution. The yield of recrystallized product was 95% based onterephthaldehyde; m.p. 220°-222° C. Its infrared spectrum showed bandsfor <C═N-- at 6.14 and 6.6μ ; for --OH absorption at 3.3, 7.1 and 7.6μ;and for ##STR19##at 8.2 and 12.0μ.

2. Intermediate Terephthalhydroxamoyl Chloride, ##STR20##

Into a suspension of 2.3 g. terephthaldehyde dioxime (A above) in 45 ml.CCl₄ was passed slowly with stirring a stream of Cl₂ gas for a period of1.5 hours. The temperature of the reaction mixture was held below 0° C.by means of an ice-salt cooling bath, then the mixture was allowed toremain at room temperature overnight. The suspended solids wererecovered from CCl₄ by filtration and were recrystallized twice from 10%ethanol-90% chloroform. White crystals were obtained, m.p. 184°-186° C.

3. Synthesis of 1,4-Benzenedinitrile Oxide (BDNO)

A solution of 16.7 g. (0.0716 mole) of terephthalhydroxamoyl chloride in270 ml. of diethyl ether was added over a period of 15 minutes to a wellstirred solution of 21 g. of triethylamine (0.21 mole) in 760 ml. ofdiethyl ether; the reaction was maintained at 0°-2° C. with a salt-icecooling bath. A voluminous precipitate was formed and after stirring for10 minutes, 60 ml. of ice-water was added to the reaction mixture andstirring continued for an additional 30 minutes. Then the precipitatewas recovered by filtration, washed thoroughly 3 times with alternateportions of cold water and diethyl ether, and then dried atroomtemperature at 5 mm. Hg pressure for 18 hours. Yield 80% of theory(9.3 g.)as a yellow powder which does not melt at temperatures up to300° C.The infrared spectrum showed the strong bands characteristic ofthe nitrileoxides at 4.3, 8.5 and 9.2μ.

Analysis: Calc'd. for C₈ H₄ O₂ N₂ : C, 60.00; H, 2.52;N, 17.50. Found:C, 59.90; H, 2.58; N, 17.37.

Table VI, below, summarized the data on the polymers so prepared.

                                      Table VI.                                   __________________________________________________________________________     Data on Dipolar Cycloaddition Reactions of Various Oligomeric Polyimides                               Molar   TGA                                         Example                                                                            Pro-                                                                              Oligomer Dipole  Ratio                                                                              %  Cured      Break                                                                             Inflection                   No.  cedure                                                                            (01) Grams                                                                             (Di)                                                                              Grams                                                                             Ol:Di                                                                             Yield                                                                             at ° C.                                                                    Atmosphere                                                                           ° C.                                                                       Point ° C.            __________________________________________________________________________    11   A   BTAS-1                                                                             0.505                                                                             BDNO                                                                              0.0190                                                                            1:1 100 200 nitrogen                                                                             320 (320)                                 (h)                      240 nitrogen                                                                             360 (520)                        12   A   BTAS-1                                                                             0.505                                                                             BDNI                                                                              0.105                                                                             1:1 107 240 nitrogen                                                                             300 (350)                                 (h)                      300 nitrogen                                                                             340 (510)                        13   B   BTAS-3                                                                             0.4478                                                                            BDNO                                                                              0.016                                                                             1:1 100 200 air    270 560                                   (i)                      300 air    380 580                          14   B   BTAS-4                                                                             0.4882                                                                            BDNO                                                                              0.0640                                                                            1:4 110 200 nitrogen                                                                             380 510                                   (j)                      200 air    380 490                          15   B   BTAS-4                                                                             0.4882                                                                            BDNO                                                                              0.0160                                                                            1:1 108 200 nitrogen                                                                             425 530                                   (j)                      200 air    400 530                          16   B   BTAS-4                                                                             0.4882                                                                            BDNO                                                                              0.0120                                                                            4:3 104 200 nitrogen                                                                             435 530                                   (j)                      200 air    375 515                          17   C   BTAS-4                                                                             0.4882                                                                            BDNO                                                                              0.0160                                                                            1:1 99.5                                                                              200 air    300 550                                   (j)                      300 air    375 540                          18   B   BTAS-4                                                                             0.4882                                                                            BDNI                                                                              0.0310                                                                            1:1 102 200 air    250 550                                   (j)                      300 air    400 550                          19   C   BTAS-4                                                                             0.4882                                                                            BDNI                                                                              0.0310                                                                            1:1 112 200 air    300 530                                   (j)                      300 air    360 520                          20   B   BTAS-4                                                                             0.4882                                                                            BDNI                                                                              0.0232                                                                            4:3 104 200 air    300 540                                   (j)                      300 air    400 540                          21   B   BTAS-10                                                                            0.440                                                                             BDNO                                                                              0.0160                                                                            1:1 92.98                                                                             200 air    390 560                                   (k)                                                                  22   B   BTAS-10                                                                            0.440                                                                             BDNO                                                                              0.0120                                                                            4:3 101.26                                                                            200 air    380 550                                   (k)                                                                  23   B   BTAS-10                                                                            0.440                                                                             BDNI                                                                              0.0310                                                                            1:1 101.57                                                                            200 air    390 530                                   (k)                                                                  24   B   BTAS-10                                                                            0.220                                                                             BDNI                                                                              0.0116                                                                            4.3 108.18                                                                            200 air    310 550                                   (k)                                                                  25   B   BTAS-11                                                                            0.2576                                                                            BDNO                                                                              0.008                                                                             1:1 104 200 air    330 555                                   (1)                      300 air    390 580                          26   B   BTAS-11                                                                            0.2576                                                                            BDNO                                                                              0.006                                                                             4:3 103 200 air    330 555                                   (1)                      300 air    410 585                          27   B   NTAS-1                                                                             0.4666                                                                            BDNO                                                                              0.016                                                                             1:1 110 200 air    350 510                                   (m)                      300 air    350 525                          28   B   NTAS-1                                                                             0.4666                                                                            BDNO                                                                              0.012                                                                             4:3 109 200 air    350 505                                   (m)                      300 air    400 525                          29   B   PMAS-1                                                                             0.4216                                                                            BDNO                                                                              0.016                                                                             1:1 98  200 air    300 515                                   (n)                      300 air    380 530                          30   B   PMAS-1                                                                             0.4216                                                                            BDNO                                                                              0.016                                                                             4:3 99  200 air    310 570                                   (n)                      300 air    310 570                          31   A   BTAN-2                                                                             0.5045                                                                            BDNO                                                                              0.080                                                                             1:1 98  200 nitrogen                                                                             200 430                                   (a)                      300 nitrogen                                                                             300 520                          32   A   BTAN-2                                                                             0.5045                                                                            BDNO                                                                              0.320                                                                             1:4 100 200 nitrogen                                                                             200 350                                   (a)                      300 nitrogen                                                                             350 550                          33   A   BTAN-2                                                                             0.5045                                                                            BDNI                                                                              0.105                                                                             1:1 107 240 nitrogen                                                                             250 400                                   (a)                      300 nitrogen                                                                             330 525                          34   A   BTAN-2                                                                             0.5045                                                                            BDNI                                                                              0.620                                                                             1:4 103 240 nitrogen                                                                             250 330                                   (a)                      300 nitrogen                                                                             340 530                          35   B   BTAN-3                                                                             0.2399                                                                            BDNO                                                                              0.008                                                                             1:1 103 200 air    300 520                                   (b)                      300 air    370 560                          36   B   BTAN-3                                                                             0.2399                                                                            BDNO                                                                              0.0320                                                                            1:4 109 200 air    300 560                                   (b)                      300 air    360 550                          37   B   BTAN-3                                                                             0.2399                                                                            BDNI                                                                              0.0155                                                                            1:1 102 200 air    320 600                                   (b)                      300 air    360 575                          38   B   BTAN-3                                                                             0.2399                                                                            BDNI                                                                              0.0620                                                                            1:4 106 200 air    320 585                                   (b)                      300 air    360 570                          39   B   BTAN-4                                                                             0.254                                                                             BDNO                                                                              0.008                                                                             1:1 97.06                                                                             300 air    430 560                                   (c)                                                                  40   B   BTAN-4                                                                             0.254                                                                             BDNO                                                                              0.032                                                                             1:4 111.09                                                                            200 air    360 580                                   (c)                                                                  41   B   BTAN-4                                                                             0.254                                                                             BDNI                                                                              0.0155                                                                            1:1 100.15                                                                            200 air    390 545                                   (c)                                                                  42   B   BTAN-4                                                                             0.254                                                                             BDNI                                                                              0.062                                                                             1:4 95.41                                                                             200 air    400 550                                   (c)                                                                  43   A   BTBN-1                                                                             0.5185                                                                            BDNO                                                                              0.08                                                                              1:1 100 200 nitrogen                                                                             170 530                                   (e)                      300 nitrogen                                                                             350 540                          44   A   BTBN-1                                                                             0.5185                                                                            BDNO                                                                              0.320                                                                             1:4 100 200 nitrogen                                                                             200 530                                   (e)                      300 nitrogen                                                                             350 560                          45   A   BTBN-1                                                                             0.5185                                                                            BDNI                                                                              0.155                                                                             1:1 107 240 nitrogen                                                                             280 550                                   (e)                      300 nitrogen                                                                             340 550                          46   A   BTBN-1                                                                             0.5185                                                                            BDNI                                                                              0.620                                                                             1:4 108 240 nitrogen                                                                             250 indeter-                                                                      minate                                (e)                      300 nitrogen                                                                             350 530                          47   B   BTBN-3                                                                             0.2423                                                                            BDNO                                                                              0.008                                                                             1:1 105 200 air    280 590                                   (f)                      300 air    360 610                          48   B   BTBN-3                                                                             0.2423                                                                            BDNO                                                                              0.032                                                                             1:4 110 200 air    310 570                                   (f)                      300 air    350 550                          49   B   BTBN-3                                                                             0.2423                                                                            BDNI                                                                              0.0155                                                                            1:1 99  200 air    320 595                                   (f)                      300 air    420 610                          50   B   BTBN-3                                                                             0.2423                                                                            BDNI                                                                              0.0620                                                                            1:4 104 200 air    320 580                                   (f)                      300 air    390 595                          51   B   BTBN-4                                                                             0.255                                                                             BDNO                                                                              0.008                                                                             1:1 97.00                                                                             200 air    400 520                                   (g)                                                                  52   B   BTBN-4                                                                             0.255                                                                             BDNQ                                                                              0.032                                                                             1:4 101.64                                                                            200 air    340 540                                   (g)                                                                  53   B   BTBN-4                                                                             0.255                                                                             BDNI                                                                              0.0155                                                                            1:1 102.33                                                                            300 air    460 620                                   (g)                                                                  54   B   BTBN-4                                                                             0.255                                                                             BDNI                                                                              0.062                                                                             1:4 98.52                                                                             200 air    450 595                                   (g)                                                                  55   A   BTAA-3                                                                             0.443                                                                             BDNO                                                                              0.080                                                                             1:1 96  200 nitrogen                                                                             220 350                                   (d)                      300 nitrogen                                                                             340 400                          56   A   BTAA-3                                                                             0.443                                                                             BDNI                                                                              0.105                                                                             1:1 105 240 nitrogen                                                                             260 300                                   (d)                      300 nitrogen                                                                             330 370                          __________________________________________________________________________    * Bracketed values are not sharply defined.                               

What is claimed is:
 1. A polymeric chain-extending process comprising:heating at a temperature in the range of about 150°-450° C. a polyimidehaving the formula ##STR21## wherein Ar' is a tetravalent aromaticorganic radical, the four carbonyl groups being attached directly toseparated carbon atoms and each pair of carbonyl groups being attachedto adjacent carbon atoms in the Ar' radical, Ar is a divalent aromaticorganic radical, R is an aromatic hydrocarbon radical of 6 to 12 carbonatoms, and n is a positive integer of at least one with achain-extending material selected from the group consisting offormaldehyde, a compound capable of generating formaldehyde under thereaction conditions and hexamethylene tetramine in the presence of about1-5% by weight, based on the weight of polyimide, of lime, and whereinthe amount of formaldehyde present or generated is about 5-25% byweight, based on the weight of polyimide.
 2. The process of claim 1wherein ##STR22## and n is at least
 4. 3. The process of claim 1 whereinAr' is selected from the group consisting of ##STR23## and Ar isselected from the group consisting of ##STR24## and multiples thereofconnected to each other by R^(IV), wherein R^(IV) is alkylene of 1 to 3carbon atoms, ##STR25## --O-- , --S-- , --CH═CH--, and --SO₂ --.
 4. Apolymeric chain-extending process comprising: heating a polyimide at atemperature in the range of about 150°-450° C. with about 5-25% byweight, based on the weight of polyimide, of formaldehyde orparaformaldehyde and about 1-5% by weight, based on the weight ofpolyimide, of lime, said polyimide of the formula: ##STR26## Ar' isselected from the group consisting of ##STR27## and Ar is selected fromthe group consisting of ##STR28## and multiples thereof connected toeach other by R^(IV), wherein R^(IV) is alkylene of 1 to 3 carbon atoms,##STR29## --O-- , --S-- , --CH═CH-- , and --SO₂ -- ##STR30## and n is apositive integer of at least
 1. 5. The process of claim 4 wherein theformaldehyde or paraformaldehyde is at a concentration of about 10-15%by weight and n is from 1 to
 20. 6. A cross-linked polymer prepared bythe process of claim
 1. 7. A cross-linked polymer prepared by theprocess of claim
 4. 8. A cross-linked polymer prepared by the process ofclaim
 5. 9. The product of claim 6 wherein ##STR31## and Ar is selectedfrom the group consisting of --C₆ H₄ CH₂ C₆ H₄ --, --C₆ H₄ SO₂ C₆ H₄ --, --C₆ H₄ OC₆ H₄ SO₂ C₆ H₄ OC₆ H₄ -- , --C₆ H₄ OC₆ OC₆ H₄ -- , --C₆ H₄OC₆ H₄ -- , and --C₆ H₄ --.
 10. The product of claim 7 wherein ##STR32##and Ar is selected from the group consisting of --C₆ H₄ CH₂ C₆ H₄ --,--C₆ H₄ SO₂ C₆ H₄ -- , --C₆ H₄ OC₆ H₄ SO₂ C₆ H₄ OC₆ H₄ -- , --C₆ H₄ OC₆H₄ OC₆ H₄ -- , --C₆ H₄ OC₆ H₄ -- , and --C₆ H₄ -- .
 11. The product ofclaim 7 wherein ##STR33## and Ar is selected from the group consistingof --C₆ H₄ CH₂ C₆ H₄ --, --C₆ H₄ SO₂ C₆ H₄ -- , --C₆ H₄ OC₆ H₄ SO₂ C₆ H₄OC₆ H₄ --, --C₆ H₄ OC₆ H₄ OC₆ H₄ --, --C₆ H₄ OC₆ H₄ -- , and --C₆ H₄ --.12. The product of claim 8 wherein ##STR34## and Ar is selected from thegroup consisting of --C₆ H₄ CH₂ C₆ H₄ --, C₆ H₄ SO₂ C₆ H₄ -- , --C₆ H₄OC₆ H₄ SO₂ C₆ H₄ OC₆ H₄ -- , --C₆ H₄ OC₆ H₄ OC₆ H₄ -- , --C₆ H₄ OC₆ H₄-- , and --C₆ H₄ --.
 13. The process of claim 1 wherein thechain-extending material is an addition product of formaldehyde and aphenol having 2 methylol functions.
 14. The process of claim 1 whereinthe chain-extending material is an addition compound of formaldehyde andmelamine having from 3-6 methylol functions.
 15. The process of claim 1wherein the chain-extending material is a substituted formaldehydehaving two --CHO functions.
 16. The process of claim 15 wherein thesubstituted formaldehyde is furfuraldehyde.
 17. A polymericchain-extending process comprising: heating at a temperature in therange of about 150°-450° C. a polyimide having the formula ##STR35##wherein Ar' is a tetravalent aromatic organic radical, the four carbonylgroups being attached directly to separate carbon atoms and each pair ofcarbonyl groups being attached to adjacent carbon atoms in the Ar'radical,Ar is a divalent aromatic organic radical, R is an aromatichydrocarbon radical of 6 to 12 carbon atoms, and n is a positive integerof at least onewith a chain-extending material selected from the groupconsisting of formaldehyde, a compound capable of generatingformaldehyde under the reaction conditions and hexamethylene tetramine,wherein the amount of formaldehyde present or generated is about 5-25%by weight, based on the weight of polyimide.
 18. A cross-linked polymerprepared by the process of claim 17.